like a fabric softener? I've never heard of anyone's bunnies have problems with that kind of thing. If its just smell you're concerned about, bunnies are pretty decisive when they don't like something. Your bun wouldn't play on the bed if the smell was bothering him. As far as health issues - I'd guess if its okay for human skin to be up against and for humans to inhale all night long than its probably pretty safe for a rampaging rabbit to enjoy for a bit of time each day. Like I said, I've never heard of anyone's buns having problems with something like that before. Maybe someone else will pop in with an answer if they have a different experience but I think you're probably pretty safe letting him go ham on your bed to his heart's content without worry.
