When you go out of town on vacation, and as soon as you get to the motel, you open the yellow pages to "Hobby Shops"

When your Master Card statement reflects all of the charges to a single store

When you put the cheapest gas possible in your $30,000 car, but you insist on at least 15% nitro for your OS 46.

When the address book in Outlook Express is almost all RC buddies!