Just leave it in a room full of smokers for a couple of weeks. You will be sure to get a nice coating of crud on the lens for that misty dramatic look.
Every year for quite some time the pro communitee here in Calgary use to have a photo contest. The rules were simple, you could only use a Brownie or Instamatic type camera, no filters and one roll of film. Any subject matter. Images were printed on 8x10 paper and then we would have a wine and cheese night to judge the winners. You would be amazed at the phenominal images that came out of these little plastic cameras! We would just have to use the limitations of the camera as a creative element. To bad we don't do it anymore it sure was fun.
I was a nice diversion from using our super sharp wiz bang whatevers.