We audit a lot of Google Ads accounts. The same handful of problems turn up in most of them, and none is exotic. They are simply things nobody was paid to look for.
Spend on searches that could never convert
Broad match plus automation is efficient at finding volume and indifferent to whether that volume can buy. Accounts routinely pay for job seekers applying for work, students researching, competitors checking prices, and people looking for the DIY version.
The fix is a negative keyword list built from actual search terms, then maintained. It is tedious, unglamorous, and usually the single largest improvement available in month one.
Conversions that are not conversions
If every page view of a contact page counts as a conversion, the algorithm will cheerfully optimise toward people who visit that page and leave. Google chases what you define, precisely, so a loose definition produces expensive nonsense with impressive-looking totals.
Worse is the account with no call tracking at all. For a plumber or a law firm the phone typically outperforms the form, and an account blind to calls is being judged on a minority of its results. Paid search looks expensive, budget gets cut, and the channel producing the most work takes the blame.
Ads pointing at the homepage
An ad promising emergency same-day service should not land on a page describing your company history. Every mismatch costs twice: fewer of the clicks convert, and quality signals worsen, which raises what you pay for the next click.
Nobody has looked at Display in a year
Display is cheap per impression, which is exactly how it accumulates spend without scrutiny. For prospecting it rarely earns its place for a service business. For remarketing it can be excellent. The line is worth drawing deliberately rather than by neglect.
Bids optimised, economics ignored
The most common failure is not technical at all. An account can be immaculately managed toward cheap leads while producing customers that cost more than they are worth, because nobody fed close rates back in.
Cheap leads and profitable customers are different goals, and optimising for the first at the expense of the second is the most expensive mistake available in this channel.