By far... the ugliest of the neo-cons in terms of raw physical appearance is Richard Perle. I mean, you try to look at this photo without recoiling in horror (if the artilcle doesn't make you barf first)-- the guy looks sort of like what would happen if Jabba the Hutt and Oscar the Grouch had a child.
Imagine being Mrs. Perle and having to wake up next to this evil tub of guts every morning. Especially when he's feeling frisky...