Quoted from thefoxxman:

To put another spin on this, on one hand it's depressing seeing the machines in this condition..dirty, worn.... but there is a reason these machines are in this condition, and that's because people ARE playing them! THAT is a good thing! Sometimes wear on the playfield is a sign of a GREAT game that people have loved to play!
These machines are doing the EXACT job that they were designed to do - be played out in the wild!
But of course, if people have a bad experience with a non working machine, it may turn them off from playing again - so that is the flip side. If the machine works and is just dirty, well not quite so bad!