Reading the white paper first is a good thing before join any airdrop program. However, the white paper that belongs to a project may not necessarily be implemented as written. There are many factors that you should make a point of choosing an airdrop, especially regarding core dev team, security of smart contracts and so on. I know, you will not lose anything if the airdrop from your analysis results if it is not distributed or has no value, but only focusing on the white paper still needs further checking.