[patio11]

Right, you understand this perfectly. With Conversion Optimizer, shaving is a non-problem: an advertiser who shaves is just doing something they're permitted to do ("bid less for clicks") via a roundabout way.

This throws people for a major loop because Google encourages people to think of Conversion Optimizer as CPA bidding and shaving is automatically a problem for publishers in CPA. In standard CPA, shaving is "not paying for services which you have already received".

Its sort of a leaky abstraction for an advertiser. Conversion Optimizer is described as CPA bidding because that is the easiest way to tell an experienced advertiser what it is. It does, indeed, feel like CPA bidding when everything is going right. But there is CPC bidding going on underneath it, and while that detail is abstracted away it can bite you in the hindquarters if you're not aware of it.