If they charge for airdrop then it is a scam airdrop campaign. While there are some airdrop campaigns that actually payout after sending a fee, it's still a risk. They can be trusted if the project is popular and good. It is better to avoid such airdrops.
why take risks with tokens/coins that will be "shitcoin/token". I have never participated in Airdrop since 2018, everything will just be a collection that contaminates the wallet, some pay but the value is much smaller than the exchange fee. it's better to just avoid all forms of airdrops that ask for fees from potential coin recipients..
if you don't participate in 2018 then what about in 2020? Did you get a thousand rich opportunities with massive airdrops like Uniswap? This is very simple, you only need to claim the token before September 1 and it's free.