My college roommate was from Minnesota where they don't have state inspections. He brought his MN registered car to Massachusetts, probably one of the most strick inspection states, and never got a ticket for not having an inspection sticker. I dunno if that's because it was never noticed (he was pulled over at least once or twice) or if the cops just never saw it. He seemed to think he was in the clear, and he's a fairly knowledgable guy.