I sometimes have abstract dreams with an irregular surface that slowly morphs into different shapes. It goes from being smooth and flat, to irregular shapes (that I find disgusting) and back into fractals or regular geometric shapes (that I find pleasant). The change from nice to ugly shape is evoking very strong disgust.

I think there is something to the idea that low Kolmogorov complexity is pretty.

I've also had a weird esthetic experience commuting by a bus once - it was a sunny winter day and along the road for dozens of kilometers there were power lines with unusually thick wires. There was a lot of contrast between white snow and black wires and they went up and down in a regular but slowly changing pattern that was very beautiful in the moment, but it's very hard to explain after the fact :) I was amazed by it despite commuting that same route 100s of times before and after that and never noticing it or caring about it.