I think it is more just considered being a dick.

In some pools your pay out is decided by your ratio of completed shares, compared to other peoples ratio of completed shares those pools really encourage pool hopping because people come in with huge rigs do a massive amount of shares over a short period of time then leave and still manage to get a good payout because when the block is finished they will still have a larger ratio of completed shares than many of the miners with weaker mining equipment. So basically they make a disproportionate amount of money compared to others.