Archie, what you describe is not only nasty, but illegal. There's been some problem with that here, out in Washington County were it's a bit redder. People with pickups stealing signs. Someone got a good shot with a cell phone camera- pic of someone picking up and putting signs into their truck, with a clear view of the license plate. If I remember right, they got nailed on theft and vandalism charges. The theft rate when down quite a bit after that.

I live in the middle of Portland. Mostly blue, but a few scattered Republicans here and there. Our problem here is not really GOP supporters, it's simply idiotic teens who think they're having fun. (We also have problems with water damage- it is Oregon, after all.) We usually put our signs in the front window, where they can't be damaged or stolen.