[robryan]

Enforce it on clients over a certain number of users where they are big enough to manage following a bunch of rules around the ads. Then they can be audited to make sure they get doing it correctly.

[MrOwnPut]

Yeah it can be done with X amount of risk and auditing ($)...

I was mainly asking has it been done by any service?

Risking your advertisers is not wise and audits will be expensive and reactive not proactive.