There are just so many airdrops. Do people just do as many as they can in no particular order or is there a way to see which are the best?
most people do just like that, register to as many airdrops as possible (because most will turned scam) 
Personally, I only claim fork share I feel can be done safely and worth claiming for, sell or hold
and only register on airdrop of a few projects that I think have good prospect in the future
There has to be a catch with airdrops doesnt it? How can people give away free money?
They generated the money from thin air (tokens), just required a small fee and setup to create 1,000,000,000 tokens or moreand they distribute/airdrop only fraction of it, the rest would be pre-ICO, ICO, pre-sale, and etc whatever they called it
then set aside some for "marketing" and reserved for "developer fund" as they said
if the project succeeded they get rich (from profit), if turned scam they still get rich (from ICO fund)