I fully believe the following
  1. They don't turn your headlights on properly.
    Best way to get pulled over and inevitably be charged with a dui
  2. They find your home address from your navigation system.
    They go into "saved" destinations and copy down your "home" address, because even though TV show watching and Jewish mother chain emails have warned you not to, you entered your real home address.
  3. They make a copy of your house key
    Because even though you have been warned by the same TV show and the same email you STILL left your house key in the car.
  4. They sell your house key and your address to the highest bidder.
    It would be too easy to connect the dots to them personally. They watch the same TV shows and have the same Jewish mothers emailing them.
  5. Their associates rob you
    Assuming you have been arrested, they let themselves into your house and help themselves to whatever they fancy.
  6. They murder you
    Because you don't drink and drive, you pass all tests with flying colours and you arrive home early and surprise the burglars in the act. You are bludgeoned to death, which is bittersweet for you and those who know how much you love the smiths.
  7. They drink from your water bottles
    Less terrifying than the situation you outline above, but once I started wondering if the valets ever do that I couldn't leave a water bottle in the car ever again.
    Suggested by @mandi