Jafar the malevolent pool owner checks for solved blocks, any only allows a percentage to go to the pool bounty, and the remainder going to his personal secret bounty. To the miner, it is imperceptible, as the cheat percent is sufficiently low.
What stops Jafar?
Can this be done with a viewkey shared with pool members? Do any pools do this yet?
Here is the answer when it comes to Bitcoin mining pools. https://bitcoin.stackexchange.com/a/10693
TL;DR: The miner will find a valid hash based on the merkle root provided initially by the pool. Once a solution is found, the miner will submit it to the owner. The owner would not be able to change the transactions (to divert the BTC to their own address) without making the solution invalid due to a different merkle root.
Presumably the same would apply to Monero, although I haven't been able to find much documentation on the structure of Monero blocks and their mining.
