I'm a bit out of the loop on SPN fandom, and I had no idea that anyone was even trying to seriously argue that Dean never expresses anger with Sam.

I can't remember the exact phrasing - it was a while ago - but it was a response to Sam fans complaining that Dean never forgives Sam in the later seasons or lets stuff go. So this fan argued that Dean holds onto his anger over Ruby/soulless/etc because he never expressed it in the first place (while Sam is more forgiving of Dean because he does feel comfortable expressing anger towards Dean).

Uh, yeah, no.

Carmen, yes. Although at least she was supposed to be a fantasy. Lisa was just...painful, and lost potential.