I could imagine somebody who is pretty self aware could judge their taste in music to be worse than average, if they really only ever buy music from artists that they are later embarrassed by.
But in general, I think this would skew towards people having the preference for their preference.
> your own music taste determines what you think constitutes good music taste
No, your own music taste determines what you think is good music. Taste is not about holding your own opinion higher than others', it's just about what you like or not.
I still find it weird that it's a 50/50 split though. Maybe a lot of people aren't thinking so much about whose taste is better, but whose is more refined? Like how people who aren't into wine might not take their own lived experience as seriously as the words of an experienced sommelier?
If that's how you interpret the question, then the whole concept of having "good" or "bad" taste is incoherent to begin with. If it's just your opinions on what you enjoy while not harming yourself or anyone else, then obviously nobody's taste can be better than that of anyone else.
Granted, starting from this interpretation could easily lead people to interpret "good" as "refined"; I suppose that makes sense.
> Do you have better music taste than average?
Of course I do. Logically everyone should evaluate their own taste in music to be better than average, since your own music taste determines what you think constitutes good music taste. Somehow, only about half of respondents selected that option, though. That's interesting.