Heeeeeeeee. I generally start wanting to punch him around the time he gives Henry a verbal blowjob in Act II scene iii, but I don't think that's "irredeemable asshole" as much as it is "irredeemably annoying"!

(Subtopic for essay question: would he be less annoying if it were an actual blowjob? I am probably not the best person to answer, for my Northumberland-hate is strong.)