There should be no harm to try out airdrop if they are giving it out completely for free. If in exchange, they are asking for something then you need to contemplate on it and decide whether you are ready to give what they are asking for. If it's just your email id then I would suggest to go for it. But if they are asking for more personal information or make some payments then it should ring an alarm in your mind.

Do you have any specific fraud experienced in any airdrop? If so, then kindly share detail so that other members can also know about it.