Short answer
Google matches ads to searches it thinks are related, and related is generous. Broad match keywords, no negatives and automated campaign types are the three usual causes. The search terms report shows exactly what you have been paying for.
Almost every plumber who looks inside their own ad account for the first time has the same reaction: why am I paying for this. Plumbing courses, plumber salary, how to fix a tap. None of them could ever have become a job.
It is not a fault. It is a set of settings doing exactly what they were told.
Where to look first
The search terms report. Inside Google Ads, under Insights and reports.
This shows what people actually typed, which is different from the keywords you bid on. Most plumbers have never opened it, and it is the most revealing screen in the account.
Spend ten minutes there before changing anything. You cannot fix a leak you have not found.
The three causes, in order
1. Broad match keywords. If you bid on plumber as a broad match, Google will show your ad for anything it considers related. Related is generous: plumbing supplies, plumbing apprenticeships, plumber near me, and plenty you would never guess.
Phrase and exact match are tighter. For most plumbers the sensible setup is phrase and exact for the money searches, with broad used carefully and watched closely.
2. No negative keywords. Nothing is blocked unless you block it. A starter list of courses, jobs, salary, supplies and how to removes a large slice of the waste immediately.
3. An automated campaign type doing what it likes. Performance Max and similar will go looking for conversions wherever it can find them. If your conversion tracking is loose, it will optimise towards the wrong thing with great enthusiasm. A plumber with a small budget usually wants a straightforward search campaign they can see into.
The fix, in order
- Read the search terms report
- Add everything useless as a negative keyword
- Tighten match types on your main keywords
- Check your radius while you are in there, because paying for clicks from forty minutes away is the same problem wearing a different hat
Then do step one again next month, because it will have drifted.
Why it keeps coming back
Because people keep inventing searches. Nobody can predict them all in advance, which means the negative list is never finished.
This is the honest description of what ongoing ad management is. Not clever strategy, mostly: it is reading what actually happened and trimming what should not have. An account with that habit and one without are paying very different amounts for the same work.
The part that should annoy you
If somebody manages your ads on a percentage of spend, they get paid more when this waste continues.
Not deliberately, usually. But the incentive sits the wrong way round and almost nobody mentions it when they quote. Trimming your wasted spend costs them money, and nobody is at their most diligent about work that lowers their own invoice.
That is the reason ads are a flat fee here. If I halve your wasted spend, my fee does not move, so there is nothing to think about.
Before you blame the ads
If the searches look right and the clicks are relevant but nothing converts, the problem has moved somewhere else: the page they land on, the phone going unanswered, or how fast you call back.
Spending more at that point just buys more of the same. This is why tracking goes in before the ads do, because a traffic problem and a conversion problem look identical from the outside and need completely different fixes.