I had a typical black rollerbag that I checked into the hotel luggage room. When I came back, it was gone. The hotel had loaded it in a cab with a group's luggage and none of those folks noticed it wasn't theirs. Somehow it made it all the way to Sacremento with them, where it went unclaimed on the baggage carousel.

A more common problem is simple delay. You expect it to take 10 minutes to retrieve your bag but it takes 30 or 40 and you need to get to the airport.

I now mark my very ordinary black bag with blue painter's tape around all the handles. It is not only easy to spot, but it looks so shabby now that nobody would want it or think it contains anything valuable.