1) the dog is comfortable with being moved manually (if you go to move the dog)
2) better yet, the dog moves when you ask her to (learns a cue to move over)
3) learns a cue to get off the bed completely when asked (I teach my dogs "off" for this cue)
4) dog doesn't growl/snap/bite/lunge (yikes!) when you get into the bed (or your partner gets into the bed)
5) doesn't pee on the bed (yeah, seriously!)
6) doesn't cause relationship issues with whomever you share the bed with (haha, ok this is on you!)
Those are my rules for bed sleeping. If your dog violates rule #4 this is the biggest issue for no-bed. This is also a totally different situation on your hands. If your dog does this you need to hire a pro to come in and help. This is a form of resource guarding. They are either guarding the bed, the space or sometimes the human in the bed if a partner comes to the bed and this sets the dog off. But do note, this is not dominance or anything related to that in the least. If this does apply to your dog, until you can get some help you should have your dog sleep in a crate or another secure room or area that is not close to the bed.
Oh and for puppy owners -- they should be fully potty trained and totally reliable to sleep all night long before sleeping in bed with you. If your puppy can sleep all night in the bed and not wake to potty or get up and wander, then have at it!
So, if you want to snuggle in bed with your pooch(es) then go for it. I love sleeping with my dogs. They warm me up in the winter and snuggle with me in the mornings before I have to officially get out of bed to start the day.
Sunshine Dog Training & Behavior, LLC