airdrops that are already on exchange are either paying small , the value of thier coin is small , listed on a bad exchange or they can pay not bad but the requirement is harder to complete that a usual airdrop  . this is why im not picky when it comes to joining an airdrop and few months ago i joined some airdrops , i only got 1 airdrop that is already on exchange but its value was verry tiny and the rest of them i havent recieved till now . they say that bountydetective has a great success rate on his projects , maybe ill consider that .