I think most people greatly overestimate how much lens flaws will affect an image. When I say "super scratched up," I mean the whole front element is covered in scratches, like someone tried to "clean" it with sandpaper. A single scratch, even a deep one, you will not ever notice. It takes a lot of scratches, or dust, or fungus, to scatter the light enough to reduce contrast. And that is the only consequence, reduced contrast. Sharpness is not affected.
My scratched Jupiter 8 blooms around any bright lights in the frame, regardless of aperture. It's kind of a cool effect, just not one I want all the time, which is why I splurged on another $25 J-8 which was not so scratched up. Even the better copy does this a little (it is 60 years old, after all), it just doesn't beat you over the head with it. These are with the scratched one.
I did have a lens once (a Cosina) with two of the cemented elements delaminating. Not only did contrast suffer, but any bloom had a purplish color cast compared to the rest of the picture. It just looked bad no matter what I did. So I try to avoid anything with apparent delamination.