I personally don't like them, but it's just a car, after all. Perhaps there should be some stricter rules about "de-copping" them before selling them off. Remove the spotlight, for starters, and anything else that makes it look like a cruiser.
When I was in the USMCR there was a guy in my reserve unit who was a cop in DC. He was talking about these old cars one day and he was bragging about how whenever he saw one, especiallyin "the hood", he would pull them over and give them crap. I asked him if the drivers were doing something illegal, and he said usually not. So of course I asked why he pulls themover and he tells me it's "because they can impersonate police officers".
I gave up trying to reason with him, as he seemed to have his mind made up and at the time we were busy and I had no time for a long argument. But two things stuck in my mind ever since: Cops will often pull you over because of their personal opinions rather than because you were witnesed breaking the law, and I do not want to be driving one of those cars. Ever. Especially when carrying.
Unless you spend the time and money and refurbish it so it looks like a normal car, you may be placing yourself in a bad situation. YMMV