Doors are sticky and noisy when opened?
By what you're describing, I assume you have paint on the outer edges of the door and the inside of the door frame. Paint doesn't make a good lubricant. And the door may not have been fitted to have the clearance for a coat of paint, or three coats if its an older house. And then when its humid and the door expands a bit, the paint rubs catches against the paint on the other surface.

If that is true, you could sand down or strip the offending parts until they clear each other without touching (and possibly repaint with a single coat if you need to). I'd expect sanding only to "rough it up" to increase the friction, not make it better.