Brandi and Jerrod were only trying to prove a point to Dave that he could be bid up too. I agree that they stopped too soon, and should have bid him up further. They should also stick him with a locker at a high price instead of giving up too soon too. That'd show him.
Brandi's enjoyment of this is what made me truly understand how brilliant and dangerous she was. She's much, much more than a harpie with a smokin' body. That said, I hope she uses that reputation and hot body to play those clowns for all they're worth, including her dolt of a hubby.