I have significant doubts about these projects, the foremost being the identities of the people conducting them. I've only seriously examined eXRP so far, and although they have a very large Telegram group, the devs don't seem active and I almost feel like the size of the group is a way to hide that fact. I don't know enough about the others (eDASH, eBTC, eLTC) but I would tread cautiously.
So what's the worst that can happen, you have worthless tokens sitting on your ETH address if you signup for these airdrops?