airdrops usually pay out on the ICO token generation date, they don;t really distribute that much coin if you want to "work" at it you should also check out some of the bounty campaign out there.
But I think it will depend on your rank or position the amount you can get from a bounty campaign, And I really think some good paying campaign really are limited for the position of a member or full member only and the case of getting your merit to be increase are very slim if you are only aiming on how much can you earn on the forum and not posting related and have good quality topic that can really be helpful in the forum and for the community.