Quality Score is Google's signal that an ad, keyword, and landing page are relevant to the searcher's intent. It affects your ad rank and your cost per click. QS is easy to see and hard to improve in a structurally broken account — because QS problems are often structure problems, not copy or bidding problems.
The five mistakes below create structural QS ceilings. The fix isn't optimization; it's restructuring. That's harder, but it's what actually moves Quality Score.
Mistake 1: Ad Groups With Too Many Intents
The mistake: a "Running Shoes" ad group with 50+ keywords covering every permutation — "buy running shoes," "best running shoes for beginners," "running shoe reviews," "waterproof trail running shoes." One ad serves all of them.
Why it kills QS: the expected CTR component of QS is measured per keyword. An ad about buying running shoes is relevant to "buy running shoes" but not to "running shoe reviews" (informational intent, not purchase intent). The ad will have low expected CTR on the informational keywords. QS suffers for those keywords.
The fix: intent-based ad group segmentation. Split by funnel stage (informational vs. purchase), by modifier (trail vs. road vs. track), or by buyer type. Write separate ads for each segment. Each ad becomes more relevant to its specific keyword set. Expected CTR improves. QS improves.
Rule of thumb: if you can't write an ad that's specifically relevant to every keyword in the ad group, the ad group is too broad.
Mistake 2: Keyword Duplication Across Campaigns
The mistake: "running shoes" (phrase match) appears in the Brand campaign AND the Non-Brand campaign AND the Performance Max campaign.
Why it kills QS: Google runs an internal auction across your own campaigns to decide which one shows. The QS signal from each keyword's performance is split — clicks go to whichever campaign won the internal auction that day, not necessarily the one that's been building QS longer. Signal stays fragmented instead of compounding.
For non-brand campaigns specifically: keywords should live in one campaign that's clearly structured for them. When the keyword is competing internally, the campaign that "should" own it doesn't accumulate the performance history it needs to improve QS.
The fix: clear campaign-level keyword ownership. Brand keywords in Brand campaigns only. Non-brand keywords in one non-brand campaign structure. Performance Max excluded from keywords that have dedicated Search campaigns (use the PMax exclusion list).
If you're unsure which of your campaigns are receiving traffic from the same keyword, run the search terms report filtered by campaign and look for the same query appearing in multiple campaigns.
Find keyword cannibalization automatically
Paste your keyword list and the auditor flags duplicate keywords, match type overlap, and cannibalization — with specific recommendations for each issue.
Free Keyword Audit →Mistake 3: Landing Page / Keyword Intent Mismatch
The mistake: "Google Ads keyword audit" and "what is keyword cannibalization" both point to the same homepage.
Why it kills QS: the landing page relevance component of QS measures whether the landing page is relevant to the keyword and the ad. "What is keyword cannibalization" is an informational query — the searcher wants an explanation. If the landing page is a commercial audit tool, the relevance score is low. QS landing page score suffers.
The fix: map keywords to intent-matched landing pages. Informational queries → educational content pages. Purchase/action queries → product or tool pages. If the site doesn't have a page that matches informational intent, write one — or exclude those keywords until you do.
Practical check: for your top 10 lowest-QS keywords (sorted by impressions), open the landing page and ask: "Is the first thing this page offers what someone who typed that exact keyword would want?" If no, there's a structure fix available.
Mistake 4: Branded and Non-Branded Keywords in the Same Campaign
The mistake: "Keyword Planner Tools," "keywordplannertools.com," branded navigational terms — all in the same campaign as generic non-branded keywords.
Why it kills QS: branded terms have much higher expected CTR than non-branded terms for the same account. The QS signal is distorted — branded keywords pull the campaign's average QS up while non-branded keywords look worse by comparison. More critically, the campaign-level budget and targeting decisions are being made with a muddied baseline. Non-branded keyword performance is harder to read, and bidding logic gets confused by mixing two very different click-rate profiles.
The fix: separate Brand and Non-Brand campaigns completely. Brand campaign: all brand-name queries, brand+modifier queries, branded navigational queries. Non-Brand campaign: everything else.
This doesn't just fix QS — it lets you bid differently on brand vs. non-brand, set different budgets, and measure performance separately. Brand CPCs can be capped low (you're going to win anyway). Non-brand CPCs can be set for conversion targets.
Mistake 5: Ad Groups That Have Drifted From Their Original Intent
The mistake: you create "Running Shoes — Beginners" with 5 tightly-themed keywords. Over six months, Google's broad match and close variants expand coverage. The search terms report now shows queries from experienced runners, trail runners, and people looking for shoe reviews — none of whom are "beginners."
Why it kills QS: the ad and landing page are still built for beginners. The new queries are being served by the beginner-intent ad but don't match it. Expected CTR and landing page relevance both suffer for the drifted queries. No new negative keywords were added, so the drift compounds.
The fix: quarterly search terms audits. Pull the search terms report, sort by cost, and check every high-spend query against the ad group it's being served from. Queries that don't match should be added as negatives, moved to the right ad group, or harvested into a new ad group with its own ad and landing page.
This is maintenance, not a one-time fix. Account structure drifts because match type behavior changes and broad match expands aggressively. The fix is the regular review.
The Structural Check
Before optimizing bids, copy, or landing pages for QS improvement, run this structural check:
- Is every keyword in an intent-coherent ad group?
- Does each keyword appear in exactly one campaign?
- Does the landing page match the keyword's intent, not just the category?
- Are branded and non-branded keywords in separate campaigns?
- When did you last audit the search terms report for intent drift?
If any of these are "no" or "a while ago," structure is the QS ceiling. Fix the structure first. QS optimization on a structurally broken account is rearranging furniture in a flooded room.