I don't think Rick Perry is dumb. I think he's probably of average intelligence. He just has the same problem that Bush had at times in that he is inarticulate at times. Nothing you can really do about that except work on it constantly. Public speaking is a skill you can improve upon so hopefully he works on that if he runs next time.
I don't think Perry is dumb either. I think "hisnibs" was just injecting Bush into it reflexively. Any time Obama or his admin is criticized, that's the typical knee-jerk reaction of most on the left. I don't even think for a minute that Bush was "dumb". A bumbler and not the most articulate guy, nor even likelythe smartest guy in the room - but certainly not "dumb".
I actually think Bush was pretty sharp. He's clearly got a sound mind and is a rational thinker. But again, not the most articulate guy in the world. That was used against him by the left and by the media to paint an inaccurate picture of his actual intelligence. Didn't Bush have better grades in college than both Gore and Kerry? And the left views those two as God-like figures, almost.