[ahazra]

I would think by giving her a treat to get off the bed she would figure out pretty quick that if she gets on the bed, you will give her a treat. I would tell her a firm NO when she got on the bed, and have her get off right away. It will take some doing, but if you keep with it she will learn that getting on the bed is no-no!

I second this. If you lure them away with a treat, they are associating a treat with a bad behavior (or undesirable behavior). Just be firm and consistent and above all patient.