i think not all of bounty campaign is wasted your time.
pick bounty campaign with sort time project and big allocation for bounty.
if you choose the good project, your time is not wasted for free.
you'll paid for your work with a good price i think.
Yes, but sometimes there will be a time that even we did our best to checked the projects sincerity and seriousness, we cannot still avoid the problem of wasting time because of turning the project into scam.