Ah this really brings me back to the old bounty days which I do not miss at all!
It never happened to me,,, I did not participate in too many though, I made the mistake of joining projects I thought were cool and did it for MONTHS to realize later they would never pay out (or tokens worth zero). Since then, I just stuck to my single campaign on here. No worries about deliveries and payments, just chat and discuss as I normally do:)
Happened to me a lot too, I participated in the signature campaign of the project, which I thought was quite cool and had no red flags. For 2-3 months, I wore their signature, and later they ended out to be a failed project lol.
For me, a deadline is a deadline, and everyone should do their best to finish their task by then. We should not fight with BM because it's not BM's fault that you delayed.