please be careful here. Many people post only a Google form. They only want their data. Often there is no Airdrop available. So always open your eyes and read. This is important. Do not give strangers your data
That is valid notice. Also, if there is only Google form and project requests donation, most likely it is a scam.
If project has recently created twitter account with 2 or 3 tweets, it is more likely scam (there will be no tokens and they collecting followers to sell account).
If project shows only social media links and no website, more likely a scam.
When there is website, check if presented team (if there is any) exists (linkedin for example) and is somehow connected to project (legit team members tend to put at least one line on linkedin that they are related to project).
Check if there is similar named account on twitter, which might belong to legitimate project and do not hesitate to contact legit project on Twitter or Telegram to validate airdrop.
Make sure you read whole form. Many times there si different token in title and different in description.
Make sure you read name of token and check if it matches social profiles. Example recent Xarum, which suppose to be Xaurum, but someone did typo. More likely it will be scam as they can't even write token name correctly.
All legit projects will respond quickly, if you approach them on twitter or telegram and in case you spot scam they will react with appropriate announcement to warn others.