I'm gathering from the conversation so far that the true "bad ballplayer" has to have absolutely no redeeming qualities whatsoever. One-dimensional contributors don't qualify in that sense, since they do have that one thing they can give the team. Exhibit A is Juan Castro -- who doesn't make the list since he he did have one redeeming quality: that famous sure-handedness.
Anyway, here's a list of names for your consideration (hat tip to this
Wily Mo Pena