This was discussed extensively on another forum that I'm on. I have never seen one and the same goes for most people, however due to some recent US legislation regarding pesticides, and an increase in travelers to the US from nations that did not have our recent agressive pesticides, bed bugs are on the rise, and even at Disney.
I do have to say that when we were leaving our Treehouse last January we ran into a pesticide sprayer guy. We had called Bell Services at 10:30 and they took about an hour to come get our bags, so he thought we were checked out already when he showed up. We chatted for about 10 minutes while he waited to get into our unit. Evidently at SSR they spray every unit 3-4 times per year. He said that spraying the regular units at SSR is not a problem, but the THV are always occupied, so he has to hit as many as he can between 11-3 which means 2-3 each day.
That put my mind at ease somewhat. But I have heard some accounts of people who had bed bugs in their rooms even at Disney.