Our department used to have a policy that you could carry whatever was on the approved list. After Hurricane Ivan, we loaned a lot of personnel to Galveston and Houston. A few months later, they remembered us when they were parting with their sig pro's. (Since then, they lobbied for a standard arm and went to glocks for all. I left before then, but the idea was ammunition compatibility. Guess what caliber they selected... Short and weak.)
Like someone else mentioned, PO weapons are carried often and rarely shot. Our 'quartermaster' sent them in to GT Distributors, who then were supposed to clean them and take care of the paperwork. 'Somehow' they all got turned into AR credit, so I missed out on a $250 Sig Pro 22xx series pistol. Check their site, they do a lot of trade-ins for Texas Peace Officers.
The one thing I can add is the condition depends on the officer who used it. I've seen a lot of PO's who never cared for their weapons beyond a monthly inspection. When it came to qualifications, there was so much gunk that the firing pin seized in place. CLICK! Nothing. (That was in a Lieutenant's holster, too. Scary!)