Juniper Research projects ad fraud will cost advertisers $172 billion a year by 2028[1], and Imperva found that 37% of internet traffic in 2025 came from malicious bots[2]. Some of those bots click your ads, and some of them finish the form.
Target CPA, target ROAS, Maximise Conversions, Advantage+: every automated bidding product
works the same way. It looks at which clicks became conversions and buys more clicks like
those. The algorithm has no idea whether a conversion was a person or a script that filled
four fields in 90 milliseconds.
So a fake conversion costs you twice. Once for the click, then again every day the
algorithm keeps steering budget toward the source that produced it.
Run the numbers on your own account: take last month's conversions, discount the ones
that arrived too fast to be a person filling a form, and recompute your true CPA. Then
remember your bidding algorithm set its targets from the
inflated figure.