Zombie SKUs: How to detect and optimize deprioritized products in Google Ads?

Managing large product catalogs in Google Ads can quickly become complex. As the number of products grows, advertising algorithms tend to prioritize items that already perform well, while other products receive little to no exposure.

These overlooked products are commonly referred to as Zombie SKUs.

Zombie SKUs are products that remain active in your catalog but receive minimal impressions, clicks, or conversions in advertising campaigns. They exist in the product feed, yet they rarely appear in search results or campaign delivery. Without proper detection and optimization, these products silently limit the potential performance of your advertising strategy.

For businesses managing thousands of SKUs, identifying and optimizing zombie products can unlock significant growth opportunities. In large e-commerce catalogs, zombie SKUs can represent a significant share of inventory, sometimes reaching up to 20–40% of products in advertising accounts.

What Is a Zombie SKU?

A Zombie SKU is a product that exists in your inventory but receives little or no visibility in advertising campaigns. In most cases, advertising algorithms prioritize products with strong engagement signals. Best-selling products receive impressions and conversions, while other products gradually become deprioritized. Over time, this creates a situation where part of the catalog becomes practically invisible in advertising campaigns.

Typical characteristics of zombie SKUs include:

• zero or extremely low impressions;

• minimal or no clicks;

• no conversions over extended periods;

• low algorithmic prioritization in Google Ads.

In large e-commerce catalogs, zombie SKUs can represent a substantial portion of the product inventory.

Why Zombie SKUs are a hidden performance problem

At first glance, zombie SKUs may not appear to be a critical issue. However, they can negatively impact advertising performance in several ways.

Limited catalog exposure

When only a subset of products receives impressions, your advertising campaigns do not fully represent your inventory. This means potential customer demand for certain products may never be captured.

Algorithm bias toward best sellers

Advertising systems tend to reinforce existing performance patterns. Products that generate conversions receive more impressions, while others receive fewer opportunities to compete.

Missed long-tail search demand

Many e-commerce searches are long-tail queries where customers look for very specific product models. According to research from Ahrefs, long-tail keywords often represent the majority of search traffic across industries. If zombie SKUs never receive impressions, these valuable search opportunities remain untapped.

Why do some products get ignored by Google Ads algorithms

Zombie SKUs typically appear due to the way automated advertising systems prioritize products. Several factors contribute to this issue:

Algorithmic prioritization

Google Ads naturally allocates more impressions to products that already demonstrate strong performance.

Large product catalogs

When catalogs contain thousands of products, it becomes difficult for algorithms to distribute impressions evenly across all SKUs.

Campaign structure limitations

Without proper segmentation or labeling, campaigns may rely heavily on algorithmic optimization, which favors historically successful products.

Performance Max automation

Performance Max campaigns rely on automation and machine learning to allocate impressions across products. While efficient, this can also lead to uneven distribution of visibility within large product catalogs.

Detecting zombie SKUs requires analyzing product-level advertising data across your catalog. Some common indicators include:

• products receiving impressions but no clicks;

• products receiving clicks but no conversions;

• products with consistently declining impressions;

• products with zero impressions over long periods.

For stores with thousands of SKUs, manual analysis becomes extremely difficult. Marketing teams often need to analyze large datasets across product IDs, campaigns, and performance metrics. Without automation, identifying zombie SKUs can take significant time and resources.

This is why many e-commerce teams rely on automated solutions for zombie SKU detection.

How does product labeling in Google Ads campaigns works

One effective way to manage zombie SKUs is through product labeling and campaign segmentation. This approach allows marketers to group underperforming products and test new strategies to increase their visibility.

The process generally includes three main steps.

Step 1. Performance analysis

Product-level advertising data is analyzed to identify items with minimal impressions, clicks, or conversions. These products are flagged as potential zombie SKUs.

Step 2. Product labeling

Once detected, these products can be assigned labels in the product feed. Labels allow advertisers to group underperforming items into specific segments that can be easily managed in campaigns.

Step 3. Campaign segmentation

Advertisers can then isolate these product segments in dedicated campaigns or product groups. This allows marketers to test different budgets, bidding strategies, and visibility levels to determine whether these products can generate demand.

For many retailers, a large portion of the product catalog remains underutilized in advertising campaigns. However, some of these products may still represent valuable revenue opportunities. With proper detection and segmentation, advertisers can unlock additional traffic and sales from previously overlooked inventory.

Zombie SKU optimization allows marketing teams to:

• expand catalog visibility;

• capture additional search demand;

• improve product-level campaign efficiency;

• discover new profitable products.

Instead of relying solely on best-selling items, brands can maximize the performance of their entire product catalog.

How G-MOS detects and labels Zombie SKUs

Detecting zombie SKUs manually becomes nearly impossible when managing large product catalogs. G-MOS solves this challenge using Intelligent Product Labeling. The system automatically analyzes your product inventory and identifies products that receive minimal or zero impressions in Google Ads campaigns.

Once these products are detected, G-MOS assigns a specific label to the affected product IDs. This label is generated through a supplementary feed that integrates with Google Merchant Center.

After the feed is updated, the labels are automatically synchronized with the connected Google Ads account. This process allows marketing teams to quickly identify zombie SKUs and create dedicated campaign segments around them.

Improving product visibility in Google Shopping and Performance Max campaigns

Once underperforming products are identified and labeled, advertisers can implement several optimization strategies. This issue most commonly appears in Shopping campaigns and Performance Max campaigns, where advertising algorithms naturally prioritize products that already generate strong engagement signals. As a result, best-selling items continue receiving the majority of impressions, while other products remain deprioritized within the catalog.

To improve product visibility, PPC specialists often restructure campaign architecture and test alternative optimization approaches.

Typical strategies include:

Dedicated campaigns

Zombie SKUs can be placed in separate Shopping or Performance Max campaigns to ensure they receive sufficient impressions.

Controlled budgets

Assigning a dedicated budget ensures that these products receive the traffic needed to evaluate their potential.

Alternative bidding strategies

Different bidding strategies can be used to test whether underperforming products can gain traction.

Catalog testing

By isolating zombie SKUs, advertisers can test whether these products can generate demand once they receive sufficient visibility. This strategy helps ensure that your entire product catalog has the opportunity to perform.

Real Example: increasing revenue with G-MOS product labeling

A practical example of deprioritized products optimization can be seen in the ZooComplex e-commerce project, where automation and product labeling were used to identify hidden product opportunities.

ZooComplex is a large online retailer in the pet products niche with thousands of SKUs on its website. Their Google Ads account reached a typical scaling limitation: the algorithm focused primarily on best-selling items. A the result, many products received little or no impressions.

Using G-MOS Intelligent Product Labeling, the PPC team automatically identified zombie SKUs across the product catalog. These products were divided into two segments:

• products are inefficiently consuming advertising budget;

• products deprioritized by the algorithm.

This segmentation made it possible to restructure campaigns and test new strategies for previously ignored products. As a result, these products were reintroduced into the advertising strategy through dedicated campaign segments and optimized budget allocation.

According to the project results for ZooComplex, this approach helped increase total account revenue and contributed to the overall 5× growth of PPC revenue for ZooComplex.

Final Thoughts

Zombie SKUs are one of the most common but overlooked challenges in large-scale e-commerce advertising. When algorithms prioritize only a portion of the catalog, many products remain invisible to potential customers. By detecting and optimizing zombie SKUs, advertisers can uncover hidden opportunities within their inventory.

Automated solutions like G-MOS Intelligent Product Labeling help marketing teams identify underperforming products, segment them into dedicated campaigns, and give every product a chance to perform.

Want to automatically detect zombie SKUs and optimize product-level campaign performance in Google Ads? Schedule a demo to see how G-MOS helps marketing teams unlock hidden opportunities in their advertising.