The short answer
The most common causes of wasted Google Ads spend are missing conversion tracking, broad match keywords with no negative keywords, and campaigns that send every click to the home page. You can check all three in your own account in under an hour.
No conversions are being recorded
If the Conversions column is empty or shows only page views, Google is optimising blind. Nothing else can be judged until this is fixed.
The search terms report is full of irrelevant queries
Open Search terms and read what people actually typed. Job seekers, free-seekers and unrelated products are budget going nowhere.
You have few or no negative keywords
Negatives stop your ads showing for searches you never want. An account with none is almost always overpaying.
Every ad goes to the home page
A search for one service should land on a page about that service. Home pages make visitors hunt, and most leave.
One campaign holds everything
When all keywords share one budget, the expensive ones take it. Separate campaigns let you fund what converts.
Location targeting includes people "interested in" your area
The default setting can show ads to people far outside your service area. Switch it to people in or regularly in your locations.
Ads run at hours you cannot answer the phone
Call-driven businesses lose leads that ring out. Use an ad schedule or a call-back form outside opening hours.
Automatic recommendations are being applied unchecked
Auto-applied suggestions can add keywords and raise budgets. Review each one against your goals instead of accepting them wholesale.
Nobody has changed anything in months
Check the change history. An account left alone drifts toward wasted spend as search behaviour shifts.
The takeaway
Fix tracking first, then negatives, then landing pages. That order usually recovers the most money for the least work.
Common questions
How often should a Google Ads account be reviewed?
Search terms weekly for the first two months, then at least every two weeks. Budgets and bids monthly.
Is Performance Max a waste of money?
Not by default. It needs good conversion data and a clean product feed, and it gives less visibility into where the money goes, so check results against a known baseline.