Being a bounty manager myself, i would have to say that these things will bound to happen.
There will sure be a scam ico that will approach a guy to ask him to do bounty manager. And if you are new, with an offer like this, i totally can understand why some guys willing to take up even though they do not verify fully. This is because it is such a rare chance, i rather take the risk than to lose a great opportunities.
In addition, if an ico is a legit one with substantial financial backing, they would have gone to more establish service providers, like my company BlockFolks. Ico service providers dont charge cheap, and one of the reason is that they will do their diligence check, meeting up with the dev team to discuss on the roadmap, give advise, have roadshow/meetups/conference to attend etc. That is why people tends to support bounties host by these service providers.