As someone else mentioned in another it is more likely for them to attempt double spends by creating alternative block chains. I recently discovered that the pool I was mining for (ABCPool) was reselling their hashing power. On fundamentals alone I decided to leave the pool and go back to deepbit. I purposely went to deepbit because I think BIP 16 and BIP 17 need more testing before attempting to implement them. I wonder who ultimately is paying this 105-115% PPS and what their true motivations are. I suggest miners take a closer look at their pool to decide whether or not they support the actions of that pool.
Another possibility is that these pools are engaged in laundering stolen bitcoins.
Please consider using
BitPenny. It uses an open-source client and coinbase transactions to assure miners that their power is not resold or abused by the server, and that all coins are freshly generated. We also believe that BIP 16 and 17 need more testing and are holding off on implementing either of them.