My friend is a poet and will be the first to say we can objectively judge art. I agree to the extent that there are certain criteria we can look at and objectively make a judgement on the quality of the work. I think bad and good are probably reductive, but we can evaluate prose or cinematography for example and make objective judgements on the qualities exhibited by the work.
I think largely though the problem here is that “good” is too vague to mean anything to anybody without expansion. Good why? There’s a difference between saying a book is good and a book is well written. Likewise if someone tells me Dan Brown is bad they’ll have to tell me why. Maybe I’ll agree and no longer like the book, or maybe I’ll agree it falls short in plot or characterization but I’ll still like it, and then it will be a guilty pleasure.
The closest you can really get to objectivity is to observe which patterns of attributes tend to correlate well to people saying that that piece of media is good. In the end, "good" or "bad" is just my emotional reaction to receiving a piece of art, and there's plenty of art that have all of the usual attributes I associate with good art that leave me completely cold.
I prefer to ask whether a piece of art is "effective" or not. An EDM club banger, a classical piano sonata, and a rap battle are all trying to achieve very different things with valued qualities coming from their various subcultures, so ask what the artist is trying to achieve (intricate composition, or shifting units etc) and judge it only in that context
I think largely though the problem here is that “good” is too vague to mean anything to anybody without expansion. Good why? There’s a difference between saying a book is good and a book is well written. Likewise if someone tells me Dan Brown is bad they’ll have to tell me why. Maybe I’ll agree and no longer like the book, or maybe I’ll agree it falls short in plot or characterization but I’ll still like it, and then it will be a guilty pleasure.