It would be wrong for someone to consider airdrops as a main job, because it is a side task when you have free time then you can work on the airdrop.
There have been dozens of airdrops that have appeared, is there anyone who can do it all? Of course not, they will also research which ones are good and which ones are bad according to their views, including myself, I am always careful in participating in airdrops.
Getting profit from airdrops is not clear, sometimes the project always delays distribution, sometimes it is not worth it after months of work, sometimes there is no value, so they must be prepared with all the risks that will be accepted later.
I doubt if there's any proven means by which you can identify if the airdrop is real or not, some airdrop that might seem legit may still end up not giving you any reward or profit. Like you already said, airdrop should not be taken that serious like a real job because it doesn't generate any significant result and could even not generate any benefit at all.