I'd say to avoid it like the plague. Some people do it to cut corners, especially on modular characters with different outfits, but it creates a mountain of problems. It's wildly inefficient and rough on performance, and skin will inevitably clip through the clothing during some animations. Even with modular characters,…
I'm working on a modular character setup right now, and I delete the body underneath the outfits. Makes rigging easier, lowers polycount... why render something unseen? I don't know of a good reason. Even if you aren't going to use the "naked body" in your game, hold onto the mesh because you'll want it later for sizing,…