There are a few airdrops where you get something at first and for the most part as satoshi or something that is convertible to satoshi, and after that once you need to pull back it, you have to pay a specific expense either in trade or out satoshi (or etherium). Is this trick or simply common? I have the feeling that once an airdrop requests any sum for whatever reasons for existing, it's a trick. Kindly right me on the off chance that I am off-base.