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.
If you are signing up for a signature or translation bounty, then in all probability you will carefully study the project before starting the campaign. But I would not say that one group studies them more than the other.