I have filled KYC for bounties but not for airdrops. If you find good bounty which have a great future in the coming days you cannot miss that chance also our ID is already present on the internet in one forum or another, so one should not worry if ICO company asks for their KYC information. But if you fill KYC for airdrop then you are wasting your time as most of the airdrop ask for nothing and airdrops can be scam sometimes, hence you should give you information for airdrops.