Man Child: Whenever he's having an argument with Carrie, he often goes to extreme lengths for petty revenge, often injuring himself or worsening the conflict. He has been shown to have a very juvenile sense of humor on several occasions, and one time fought with his father-in-law over a toy in his cereal box, just to name a few things.
Hypocrite: In "Precedent Nixin", Carrie doesn't want to stay at Doug's parents' apartment at the retirement estate, so they both wind up in a motel during Spring Break and their bathroom has a bat in it. When Doug points out that he has to deal with her father's insane antics every day, while she refuses to spend a weekend with his, Carrie dismisses Doug's argument.
Disproportionate Retribution: A waitress is constantly seeking advice from him. He gets fulfillment from this, until finding out from a dimwitted co-worker that she only does so to follow the opposite of what he suggests. Following this he deliberately sets her up to follow bad advice (or ignore good advice). Whether or not he intended for this to get her fired and potentially bankrupt, he seems to find her outcome perfectly just in his gloating.
Former Waitress: You cost me my job! How am I going to pay my bills?!
Arthur: And you hurt my feelings, so now we're even!
The Load: He contributes nothing to the household and in fact has cost the Heffernans significant amounts of money (Started fires, sold their furniture when they are away...etc.) and stress (goes through personal belongings, keeps them awake at night when moved across the hall, constantly yelling and trying to force his rules on them...etc). Whenever he comes across some money like bingo winnings, he doesn't even think to offer Doug and Carrie any of it for something such as new appliances they all use and has to be more or less told to give it to them. Doug wants him out of the house for these reasons but Carrie defends him, claiming he isn't that bad (which is odd, as it has been firmly established that he was a terrible father).
Coupled with his Cloud Cuckoo Lander status when Carrie once begs him to act like a human being at a corporate party, and he bluntly says "No".