OK so I am going to come to Ohgren's defense a little here!
I don't really get the whole "I hate Oghren" stuff. He's not a favorite of mine at all, but I really wouldn't call him hateable. Pitiable ? Oh yes definitely. I do admit that I think his character was more likable in origins than in awakening, but he really isn't all that bad. The belching is really the only thing about him that annoys me to the point that I wish I had an Oghren mute button.
He serves a purpose though in the game and I believe he serves it well. Being a grey warden ultimately means that you might have to sacrifice your life for the greater good at some point. Let's say hypothetically your in a situation where you have another archdemon on your hands and someone once again is going to have to take the killing blow. Lets say yourself, Alistair, anders and Ohgren are in a group and one of you have to go. Who are you gonna pick ? Just because you can get by without Ohgren for now, doesn't mean that you might not want him around later.
For all you that hate Ohgren and decide to give him the boot early on in the game, than that's your choice. I for one am going to take all the grey wardens that I can get whether or not I totally agree with their lifestyle's. This is a game after all, not a breakfast club.
And furthermore you might hate Ohgren and all his antics, but remember that Ohgren lives in a world entirely different from the real world. Look at all the crap he's gone through. Stuff that no-one could possibly imagine going through. He isn't just another vulgar dead beat dad at the neighborhood bar, hitting on women and drinking all his money away because he's a fat lazy selfish excuse of a person.
Maybe he figures that killing darkspawn and potentially giving his life for the greater good will be the only good thing that he could possibly do for his son. I mean would you want your kids around someone that drinks, kills darkspawn, and hits on women for a living ? Maybe that's Ohgren's way to deal with everything, It's not like they exactly have warrior group therapy in Dragon Age.
So, you know, maybe give Ohgren a chance people! You start this expansion out as the only Grey Warden in Fereldon ( Im not really counting Alistair bc he's either king or MIA ) So I'm thinking you might need all the grey wardens you can find. It's not like Grey Warden is equivelant to the moral highground.