It's the opposite here in Boulder; nicer Colorado cars seem to attract less attention from the police than ratty cars or out-of-staters. I think it's a combination of the presence of a lot of nice cars here and the police paying special attention to college students, who tend to not own nice vehicles unless they're Californian.
I haven't been stopped once in my 5 months daily-driving the Crossfire, and I was stopped twice for obvious DUI-hunting ploys ("changing lanes too fast") in the 4Runner in the 5 months prior, which I suspect is because the car looks a lot more like something a college student drives.
Interesting to hear about how the behavior of the police changes depending on area.