Google AI Max for Search: Common Mistakes and How Agencies Avoid Them

Google introduced AI Max as a one-click option inside standard Search campaigns. When enabled, it adds three things. Search term matching uses your keywords, ads and landing pages to find related queries, similar in spirit to broad match. Text customisation generates headline and description variations from your site and assets. Final URL expansion can send users to a more relevant page on your site than the one you set.

It also gives controls: brand inclusions and exclusions, location of interest settings at ad group level and URL exclusions. Google reports AI Max results with their own match type label in search term and keyword reports. Details continue to change, so check the Google Ads Help Center for the current setup.

Six setup mistakes appear repeatedly in account audits. Each one is easy to avoid if it is checked before launch.

Mistake 1: enabling it with weak conversion data

AI Max relies on Smart Bidding signals. If conversion tracking counts page views as conversions, double-counts leads or misses offline sales, the system optimises toward the wrong outcome at greater scale.

Before enabling, audit conversion actions in Google Ads under Goals. Make sure primary conversions reflect real value, enhanced conversions are configured where possible, and offline conversions are imported for lead businesses.

Mistake 2: leaving brand and URL controls empty

Text customisation and URL expansion can pick pages or wording you would not choose, such as a careers page, an old promotion or a blog post with weak commercial intent.

• Add URL exclusions for careers, legal, support and outdated campaign pages.
• Use brand exclusions to stop matching competitor brand queries if that is your policy.
• Use brand inclusions in campaigns that should serve only branded queries.
• Review your site’s content, since the system reads it to write ads.

Mistake 3: not reading the search term report

Expanded matching will find queries you never targeted. Some will be valuable, some wasteful. Advertisers who do not check the report each week end up paying for irrelevant traffic for months.

Filter the search terms report by the AI Max match type. Add negatives for irrelevant themes, and promote strong queries into their own keywords or ad groups if you want tighter control over them.

Mistake 4: testing without a proper comparison

Turning on AI Max in all campaigns at once removes any baseline. Results may rise or fall because of seasonality, budget changes or competitor moves.

Use a Google Ads experiment where available, splitting traffic between the original campaign and a version with AI Max. Run it long enough to collect a meaningful number of conversions, often several weeks for smaller accounts, and compare cost per conversion or return on ad spend, not clicks.

Mistake 5: pairing it with the wrong bidding

AI Max works best with conversion-based Smart Bidding such as Maximize conversions with a target CPA or Maximize conversion value with a target ROAS. On manual CPC or click-focused bidding, expanded matching can bring volume without a clear value signal.

Mistake 6: forgetting the landing page experience

Final URL expansion picks the page that seems most relevant. If your site has thin category pages or slow templates, users land somewhere weak. Improve key landing pages first: clear offer, fast loading within Core Web Vitals targets such as LCP under 2.5 seconds, and visible next steps.

Accounts with very small budgets, few conversions or strict regulatory wording, such as some finance and health advertisers, may be better served by tighter keyword control. If every word in an ad must be approved by compliance, text customisation needs careful limits or should stay off.

Choose a campaign with stable spend and at least a few dozen conversions a month, so the test has a chance to reach a clear result. In Google Ads, go to Campaigns, then Experiments, and create a custom experiment that enables AI Max in the trial arm while keeping budgets and bidding identical.

Agree in advance on the primary metric and the minimum difference you will act on. Avoid changing ads, budgets or landing pages in either arm during the test. If you must make a change, apply it to both arms on the same day and note it in the experiment log.

Before launch, write a one-page checklist the whole team can follow.

• Primary conversion actions confirmed and values checked.
• URL exclusions and brand controls added.
• Experiment created with identical budgets and bidding.
• Weekly search term review scheduled with a named owner.
• Decision rule written down before results arrive.

With this in place, the experiment produces a result people trust, whichever way it goes.