@Kyama3 I definitely think it depends on the dog, I let mine outside only under close supervision and if she gets into anything that might be gross, I give her a bath. Otherwise, she's an indoor dog that doesn't hardly shed, and I brush her teeth every night. I don't think it's bad for her to be laying in my bed, hygiene-wise. If you have a big dog that runs around in the woods and sometimes kills squirrels and stuff like that, yes, I'd be much more weary about them being in my bed. It's a personal preference, at the end of the day.
I definitely think you should set a precedent for how it will be and stick to it. I mean, don't let your dog in your bed one day when you think he's clean, and not the next when you think he's dirty. I think that makes them sad to be given something and then denied it. Mine would cry at my door for an hour if I denied her sleeping in my bad now, I bet. So I would recommend making a firm decision on what's right for you, and stick to it. And make sure, if they aren't sleeping in your bed that they have a nice place elsewhere to sleep.
