It's down to perceptions.
If I wanted to write something that sounded good I'd first gauge what sounds good to that particular audience then try to emulate it: analyse its qualities and apply them. A good example is Epic film music. I'd listen to it, take a guess at the orchestration, ask people about things like reverb and production; buy a decent sample library and daw. (I hate modern corporatised film music so rarely enjoy the proud efforts of those who present it LOL). Then I'd find a way of testing the reception of what I've written.
If I wanted my music to sound good to a "classical" or romantic audience I'd learn good CPP, practice writing coherent tunes and study the scores of the greats to learn their orchestral technique.
What sounds good to an Adele fan probably wouldn't to a Mahler fan and vice versa.
The audience for my music is small. I'm obviously pleased when someone claims they like it but it doesn't matter if people don't. Question is, am I satisfied; is the piece as I hoped?