I think the best way to know about bounty and airdrops are in the ICOs Telegram channels. It is worth it to do a little research to find good ICOs. There is SCAM, but there are also some very good projects.
There are already websites where you can find listings with ICOs (icodrops.com, icobench.com, theicorush.com and a lot more) where you can also find info about bounty and airdrops instead of entering every ICO website. However, I recommend checking the Telegram channels and ask questions even after you find something in those websites