I've joined many bounties myself. Can't blame the bounty hunter some come from the bounty manager itself who created a bunch of Fake entries and claim lot more than others.
I manage a few bounty campaigns in the past I've seen many fake entries from the same people who try to abuse the campaign. Strict rules need to apply for a Bounty campaign.
and for the dumper, this problems kinda hard to be controlled. Maybe if they start paying using ETH, LTC or BTC that probably will solve this issues.
Honestly, it is true that people create fake account all because they want to get higher stakes and all that.. but it is very alarming to hear that bounty managers fill in many fake accounts so as to get the tokens to themselves. PS i don't think paying in tokens isn't a wise decision because as people gets to trade the token, volume increases and it gives the token more value.