I haven't culled quail yet but from what I'm seen online it's just easier to skin them. Also, from what I've read they've very slippery skin, like squirrels or rabbits, you can just peel it right off.
When I do mine though I intend to pluck first (to save feathers) and then skin them off like normal.
As an aside, might I ask how you killed yours? I believe the snip method is very quick and easy but I'm not wanting to hold them, nor leave them (rather, nerves) twitching on the table. I'd like to move from quail to quail so the process is fast, efficient & less troubling for the waiting quail.
I've thought of making mini culling cones like with chicken, does that sound at all silly?