[JeffL]

Yeah, in 2004, I could get a new paying user from Adwords for $35. Since about 2007+, the cost seems roughly infinite no matter how I try to tweak it.

[TAForObvReasons]

is that an indictment of adwords or the state of the browser ecosystem (where potential customers are running ad blockers or otherwise avoiding ads)?

[Nextgrid]

It could very well be that real users are disregarding ads (either with technical solutions such as blockers or by just ignoring them) and fraud has picked up the slack so that overall the number of clicks hasn't changed but the ratio of real user to fraudulent user has changed significantly.