Could be higher now, the market is down and investors are not looking for new coins so those developers they are just gone after getting funded we have so many projects recently that scammed so many investors like Adab IronX, if the project is scam so are the bounties, you will either not going to get it or if you got it it will have no value in the market.
I was also going to post this 90% is less now they are nearly 98% or 99% as most of projects are not good and attractive and investors also have nothing serious in them most of them are just waste of time nothing else I also have many thousands coins with no worth and they will never been in good in future.
Why the percentage of scam might have increase is the reduction in IEO/ICOs as a whole. Smart bounty managers that can analyse project and detect scam are virtually inactive, so the available bounties are mostly handled by inexperienced bounty managers. Asides the fact that they cant recognize scam they also dont know how to strike a deal with good reward, cant have token in there custody or hand it over to escrow. They are also push around by bounty participants with bad decisions.