Take this from someone who was cursed with dented rims for most of his 40 year riding career. Every time I had new wheels I dealt with the worry of when and how the dent would come. Usually it would be a rain filled pothole that I didn't see or the other favorite culprit, a railroad crossing.

Anyway there's lots of latitude about what's OK and what isn't, but here are two main considerations.

1 - do the sides bulge and cause pulsing when you brake? This must be fixed otherwise you'll have poor brake modulation and risk the wheel locking in an emergency stop. A decent mechanic can get it reasonably smooth again with a hammer and file, or at least down to a tiny pulse which wears smooth over time.

2- do you feel the hop (or drop) with every revolution as you ride? What's acceptable here is strictly up to you. If it's slight and doesn't give you migraines, no problem. Or, if worse, it might get to you over time, motivating you to shell out the dough for a rebuild. (then you can be like me and wonder how long your luck will hold out this time)