Though I haven't participated in many airdrops! If I count, then I think I have joined in 20 Airdrop campaigns. Five was very successful, but they all are not available now, because they scammed! I participated in Ibtc, litecoin gold, Rebel, Bitcoin White Airdrops, I mean this airdrop was hit. At this moment, Ibtc and litecoin gold scammed. So, I can say not 99% Airdrops are a scam, there has some good airdrop campaign, but their rewards are too little nowadays!