It depends on the coin you are in. Most airdrop are from shit coins trying to get a quick buck in etherdelta, but fortunately there are legit ones. You just have to DYOR to decide whether to hold or not. There have been a number of XXX coin ETH version of coins going out lately and obviously they're all shit coins (Etherreum Dark, Blue really??), but there are also legit ones like DeepOnion. They are on round 16 out of 40 and the airdrop rules have changed so far to help accomodate new entrants. The previous system for airdrop participants requires around 10 posts/ week to help promote the coin but right now it was dropped to 5, and the application process was re-worked so that it's easier to join. It's a pretty good coin with a large and solid community, great developers and user interaction and most of all an outstanding product. It's geared towards privacy (which is a must in today's government tracking efforts) and a whole lot mroe of features for a secure transaction in the blockchain. I suggest you check them out and decide for yourself. I'm personally rooting for them to be one of the top tier coins in the privacy sector in the years to come.