[geocar]

I don't think that's quite right.

When three-letter television companies will buy an audience extender from one of these shady guys rather than tell the advertiser that they don't have as much traffic as they projected, you don't really even need to worry about detection.

There exist passive techniques powerful enough to really map these kinds of actors out thoroughly, however the industry has been reticent to stop it because everyone from Viacom to Google has facilitated ad fraud, and there's this fear that stopping things too abruptly will cause advertisers to lose faith in this (still nascent) $60 billion dollar industry (US numbers).