what is the best method to know SCAM [AIRDROPs] 
PROJECT
Know the purpose of the project usually scam airdrop only has a standard purpose such as ==> Bitcoin on Ethereum, Litecoin on Ethereum or Other PROJECTAvoid Airdrop that require donations! Airdrop scams usually require donations from participants and it has violated the notion of Airdrop
no, its not. airdrops which requires donation are not all scam. the main reason why they are doing that is to avoid cheater or the ones who abuse the airdrop because of multiple claims. though some are requires you hold a certain amount of eth on your wallet in order for them to send the coin without charges or fees , in short your going to shoulder the transaction fees. @op i dont really understand your question. do you mean your going to scam an airdrop project? no, you cant scam them rather they can scam you.