I don't think he was. It has been speculated that he was high on some pain killers due to a back injury.
Pain killers and alcohol will definitely make one sound like that.
It would definitely have to be a mix. I'm three days in on a sweet script of 10mg percocets X2 every 3 hours for my back and the only thing its affecting on me is I get itchy as hell. When you actually have the pain, you don't really get that messed up. If I smoke a bowl with it, I get a little silly, but nowhere near inebriated.
You can take snippets of any prolonged speech and make the speaker look bad, crazy or such. Dean looked like a lunatic but the people who were there say he was in context with the moment. Same with Perry, he was feeding the crowd.
Perry seems like a Bush part deux though. Have you really listened to Newt ?
Newt-Cain, Cain-Rubio, Romney-Bolton?
Nein! Nein! Nein!