My primary character has killed both House & Ceasar and sided with Yes Man. Not only did Ulysses not mention this despite apparently paying very close attention to my actions in the mojave, he decided that I'd actually sided with House, a man I had killed. Hespent a very, very long time telling me how corrupt and worthless vegas is. I really wanted a dialogue option that said, 'what are you talking about I've already shot him dead you dumb [censored]'.
It would have been nice to have had these actions mentioned, them being a quite a big deal an' all, just like Joshua Graham will in HH if you've killed ceasar.
I guess the reason is because the script that deals with this only takes into account your faction rep points and there would have been too many variables to take into account if they tried to include who you may or may not have killed.