I think the several experiences in working with different projects has made bounty hunters very experienced. They can determine a good project from the start but some of the investors are just new and do not really determine a promising project from a scam and in the end scammers run away with their money. So bounty hunters who invest in ICOs will never invest if they do not trust the project.
You could say the same thing about bounty hunters that are new to bounty campaigns. Ofcourse that someone with experience can make a better judgement if project is legit or not, doesn't matter if person is experience bounty hunter or investor.
Also, bounty hunters are for me investors too, because they are investing their time into project, which has its own value too.