I have a pair of 10" rear ones I bought from NAPA years ago and one is warped enough that the wheel can't be tightened down all the way flat. I put it on a project car and hand tightened the lug nuts with a short wrench just so the car could be pushed around and the lug nuts on one wheel kept backing off just from pushing the car around by hand.

The drum face warpage is not visible to the naked eye, but when you lay the brake drum face up on a flat table and put a bare steel wheel on it the wheel teeter-totters on the drum face. I did not discover this fine situation until it was way past the 30 day return policy + I already painted them cast iron gray so I was stuck with them at that point. Not much you could really do to fix it short of putting it in a lathe, which I don't own, and then hope enough metal is left so it would still be safe to use.

I also noticed the center eccentric hole flare on these was pretty big. Like as in why is that needed when the factory did not. It fits tight on the axle, but it does stick out enough that it may also cause issues with steel wheels.