As most intelligent and informed people know, there is a difference between stuff you like and don't like, versus stuff that's good and bad. There's also usually a significant amount of overlap.
There's plenty of bad stuff I like, and plenty of good stuff I don't - and vice versa.
For us musicianly types, we should be a little more informed as to what makes good and bad music over most non-musicians, although the parameters will vary depending on who's making the value judgements. However, that's completely irrelevant to whether something is liked or not, and we don't have any right over what anyone else should or shouldn't like.
There's also plenty of stuff I wouldn't normally like, but in an appropriate context might appreciate/like more than normal. For example, I've listened to some trancey repetitive dull dance stuff which does little to interest me at home, and yet in a club situation, found similar tracks to be great there and then, and have thoroughly enjoyed them.
It's all down to this complex thing we like to call "the human experience".
And I personally can learn something from *every* piece of music I hear, whether good/bad/liked/disliked. You can always take something away from anything...
I'm not convinced that there's any difference between 'good and bad' music and 'liked or disliked' music. Both are purely subjective terms unless you apply your own criteria.
'Bad' music to one person might make a lot of money for another and therefore is 'good' music.
Music which fails to achieve what the composer intended, might still have some appeal to a listener, despite the failure of intent. Is that good or bad music?