Regardless of whether or not you think some of us in this thread wear tin foil hats or not, this forum, and the bitcoin community as a whole, would be better off assuming MtGox DOES compete with its customers.  I personally think it's almost a certainty they participate in the markets, which means that there's a reasonable chance they do something underhanded (simply because they can).  To address your actual point, there would be huge money to be made in front-running the Darkpool orders who think they are safe from the eyes of the public.

I'm not accusing anyone here, I'm simlpy stating that I've seen some weirdness on MtGox as well, and I'm NOT going to give them the benefit of the doubt.  Other exchange owners seem to agree with me as well, like Jered from Tradehill.

I think a site should absolutely disclose if they are dipping into the markets as well, and I think everyone on this forum should get on board.