I'm sorry - I can't help it. My first remark would be that "Yea - they'd be well oiled from all of the doughnut grease!"
But that's just a smart aleck remark and disrespectful to all the LE who actually do work hard and put their lives on the line - which we all do greatly appreciate their efforts and sacrifices.
I've never bought one but I did have a chance to see some revolvers that a gun dealer I know purchased to resell. Yes, they had some scratches and handling marks, holster wear, etc. but they were actually all in very nice shape - crisp actions, good bores, etc. I'm guessing that they were probably turned in and the PD had gone to semi-autos. I wouldn't hesitate to buy a trade in - how is that any different than buying a used handgun that somebody has put a number of rounds through? Once in a great while, you might get a lemon but I think overall, you'd be fine.