Most places agree that a lot of RVs can last for up to 200k miles (and even beyond) with proper maintenance. If you're looking to buy used, you should know that high mileage is usually considered to be between 100k and 200k miles, but that's not the only thing you should pay attention to. If these miles were put onto the vehicle in a short amount of time, that's also a red flag as the vehicle may have sat idle for a while which can cause all kinds of problems. As always, ask questions and be prepared to look around and ask for a test drive because used RVs can last for a long time.