Work from the actual search terms report
The Google Ads Help Center explains the difference between a search term and a keyword, along with the visibility limits: some low-volume terms aren't shown for privacy reasons. So the report is useful, but it is not a complete log of every query.
Review spend, clicks and the agreed conversion alongside each term. Read the query together with the service, the location and the landing page. The same word can be a good fit for one service and wasted money for another.
Look for categories of mismatch
Group irrelevant inquiries by cause: a different product, research or learning intent, job seekers, a location you don't serve, or a service format you don't offer. That way you fix a pattern instead of endlessly adding random phrases.
Say a business does installation but doesn't sell spare parts. Searches about buying a part need their own decision. At the same time, the word "price" is not automatically irrelevant: it can signal someone getting ready to order.
Test negative keywords before you apply them
A negative keyword can block useful searches if its context is too broad or it sits at the wrong campaign level. The matching rules are covered in the documentation on negative keywords. Check each one against specific queries instead of blindly applying the logic of regular keywords.
Log the date and the reason for every change, and tag campaigns with UTM parameters. Afterwards, look beyond lower spend: check the number of qualified inquiries too. If demand you actually want has disappeared, go back to your exclusion list.
Google Ads management includes this kind of regular review. If the clicks are relevant but the page doesn't answer the query, what helps is a review of the site's structure and content, not just more negative keywords.
