The majority of bounty campaigns are only introducing spam on bitcointalk. So, I hope they're not going to be here for long.
They are ran by weak managers and don't care about quality or keeping the forum a good place to find useful information.
But, let me remind you that even top bounty managers can get scammed as well. Bounty Managers are not gods who can see scams right away. They need to review and review the whitepaper in order to avoid scams. There are also low-rank bounty managers that can manage bounties well.