Doesn't matter--nobody's going to hear it, and if they did, then there is no solution but to buy something better.
Being bad on purpose doesn't mean it isn't bad. I don't think even the euphonic-distortion crowd would be happy with the >1% THD that I see on that plot, but in any case, the manufacturers of those products probably claim far better. Power-line intermod that's 50 dB below that doesn't seem the worst sin there.
An otherwise transparent amp with that same crappy power supply and resulting intermod would report a distortion peak of -90 dB, which actually isn't bad. But it would report that in all of Amir's test cases of clean(ish) power, distorted power, and dirty power. The intermod is baked in, for better or worse, not the product of crappy supplied power.
Rick "not interested in noise above about 24 KHz" Denney