It's funny, but I've noticed that as my musical tastes have broadened over the years, the line between what sounds "beautiful" and "ugly" has become considerably more blurry. I can still recognize particular harmonies as consonant or dissonant, but that mapping in my brain where consonant -> beautiful and dissonant -> ugly has started to really break down.
One of the first times I noticed this was happening was probably 15 years ago, listening to Salomé by Richard Strauss. The last scene has this incredible dissonance, a polychord that's an A7 with an F# stacked on top: two chords that absolutely do not belong together in any diatonic piece of music.[1] When I first heard that I thought it sounded awful. Now it has a kind of strange beauty to my ears and is one of those musical moments that always sends a shiver up my spine.
[1] Give a listen here if you like: https://youtu.be/Op1VoQXXARs?t=431 I started the clip at 7:15, the chord comes in around 8:53 but that whole section is shot through which these ugly/beautiful sonorities.