This is a manifestation of the decline of the market. It seems that ICO model has been difficult to finance enough money now, so these ICO-based bounty, the risk of not paying is also getting higher and higher.
It's hard to find a satisfying bounty /ico now,how long do you think the bounty can live?
I believe that you don't have to focus on those 90% of the bounties, you just need to focus on 10% of the legit projects that are following the main stream. What does that mean ? That means you just be focusing on the ICO projects which are really taking the efforts to become that top 100 entity and makes things easier for you as well as for those founders and dev teams. Since long time we already know that most of the projects are scam one and hence we must not care about them but just keep trying for the best. If the scam ratio is more then all you have to do is have some extra bounties in your folio and work on them too.