For beginners in careful participation in airdrop, easy way of knowing the airdrop scam:
1. Airdrop type sent 0 ETH
2. Airdrop type form
3. Airdrop by requesting to enter privatekey
4. airdrop type Sent 0.001ETH - 0.1 ETH
5. Check official twitter DM admin if he held airdrop.

it's some of the characteristics of scam airdrop be careful in using email do not use the primary email connected to the exchange.