M.F.
Well in real estate we use the phrase "please remove your shoes, you may be stepping into your new home", not sure that would really work for your situation. I don't think you are a crabby jerk for wanting to keep your house nice by any means. You can make a sing on your computer that plainly says "please remove your shoes" you can put some clip art on it with a pair shoes (something like a no smoking sign). I wish I had a creative way to do this as well, I will be watching for some unique ideas as well.