The Ravenloft villains came unpainted, but the Drows band and monsters came prepainted. I stripped the paint down, but I regret it now. The very thin drows minis lost a bit of details in the process, and now painting them take too long for simple grunts/minor NPCs. A few details additions would have been suficient, in my opinion.
On next prepainted D&D minis I have, I'll just go for some details, but keep the prepaint on them. It's particularly true for the globins warband box. These minis are alread pretty nice, for prepainted minis.