Depends, if I am the Skins, Seahawks or Chiefs, I like my QB play with Campbell, Hasselbeck (if healthy) and Thigpen, so I wouldn't even be in the bidding. I would use my picks to build other areas on the team which need improvement.
With the Lions, my main piece is Calvin Johnson, I have a solid rookie back this year who showed flashes, I could trade a first rounder for cassel, or use those picks and try to rebuild my team from the trenches out with a solid 2-3 year plan and try to compete in a few years, since Cassel won't turn me into a contender over night, so I might give Stanton (I believe thats the rookie they drafted) a chance to grow while building around him.
The other teams, I would have to do some roster research, see what I would have for players, picks, cap space etc. Some bad teams QB play isn't an issue, or if it is an issue, its because of a temporary problem, like Carolina last year, that will fix itself once injuries heal. The main teams that I think that would be looking at Cassel are San Fran, the Jets (even though we would never do business with them,) maybe Minnesota if Tavares Jackson crashes and burns in the post season, and maybe Cincy if Palmer is finished and unable to return to form, and Chicago if the don't want to deal with Orton.