I've looked at Facebook walls of people participating in bounty campaigns and there is nothing else than 20-30 bounty posts per day. These are never real accounts with any actual followers.
I recently had access to the analytics of an ongoing ICO and was shocked to discover almost no traffic was being driven to the ICO site by bounty hunters. Maybe 1 hit for every 30 participants, per day. Upon further inspection I discovered exactly what you mentioned: most Facebook participants had completely fake pages with fake friends, same thing with Twitter: fake followers.
Unless somebody pays careful attention to quality control I don't understand how the employment of bounty hunters is at all profitable. It seems massively un-economic.
I agree I had a lot of facebook friends who are into bounty campaign on Facebook, and they posted 5 to 10 ten times about ICO they are promoting, I had to unfollow some of them although we remain, friends,, it's more rewarding if these ICO go for article marketing, and signature campaign, that is why they both pay high rewards.