A simple look enough of their profiles revealed that, like would he expected from any fly by night CPA network, FB was using bots, or at least straw man accounts run by low-cost staff, to like and view content which FB was paid to advertise.
Worse, I found that the clickthrough metrics reported by them to off-FB destinations I advertised NEVER was anywhere close to what was reported on the destination, including when tracked by Google Analytics.
In short: like-fraud, click-fraud, and more.
I cannot be the only person to notice these things. I assume it persists because most people, self included, simply complain and move on once we notice the “game” but don’t sue.