From my experience you should look for a bounty program that pays per rank, not per post. I got scammed by ChangeBank because I only got about 1/5th of the deserved amount, and I wasn't the only one by far, and the team doesn't even address my questions. Currently I'm doing bounty for Adbank, which is a lot more communicative team and I'm positive they'll handle the situation a lot more professionally
some campaigns set a rules whether its a pay per post or pays per rank , they are still the same. also most bounty campaigns are known to be scam because there are so many unkown ico's nowadays and the campaign manager that runs a campaign are mostly newbie ranks and some members that doesnt have a good reputation yet on the forum. thats the reason why i stop joining on those bounty/ico campaigns on altcoin section and id rather now foccus on the signature campaigns that pays in bitcoin weekly because those campaigns can always assure and guarantee you that they will pay.