Personally, I think she plays up the crazy for the show. Otherwise she's irrelevant and would get cut. To me, this shows her level of desperation to stay on.
Something I found interesting that hasn't been mentioned is that each season Brandi seems to endear herself to a different older woman. First it was Lisa. Then it was Yolanda. What happened there? The season doesn't start out with them being chummy like last season? Now it's Kim. I don't think Lisa, definitely not Eileen, will play the Mom role for her next season.