Yes, they can, but not in the way most people think. Display Ads don’t directly compete with Search Ads in the same auction, but if you're running both in the same campaign, there are definitely performance ripple effects.
Quick context:
If you’ve created a campaign that targets both Search and Display networks, Google allows that under what they call a Search Network with Display Select (SNDS) campaign, although it's not recommended for serious advertisers anymore.
Here’s how Display can affect Search performance in the same campaign:
Budget Competition
Both networks share the same budget, so if Display eats up more impressions (especially with cheap clicks), your Search ads might get limited delivery. It dilutes your spend across two very different channels.
Skewed Performance Metrics
Since Display usually has lower CTR and lower conversion intent, your blended campaign metrics (like overall CTR or conversion rate) may look worse than they actually are for Search. This can throw off optimization decisions if you're not segmenting data properly.
Lower Quality Signals
Display traffic can sometimes send lower-quality sessions (especially with accidental clicks), which might affect your downstream conversion data, leading to incorrect bidding or budget allocations if you're using Smart Bidding.
Less Control Over Targeting
Search is all about user intent. Display is about audience behavior and placement. Combining the two limits your ability to isolate and test effectively, and may confuse the learning algorithm.
What to do instead?
Always separate Search and Display into different campaigns.
That way, you get:
Clearer data
Better optimization control
Accurate ROAS/CPA reporting
Smarter bidding adjustments for each network
Bottom line:
If you're seeing erratic performance in a mixed network campaign, Display could absolutely be messing with your Search results. Keep them separate for best results , different networks, different behavior, different strategies.
