Is there such a thing as good taste?

I'm answering your question with a question because the difficulty of the evaluation process is the point. But there can be an evaluation, and there can be an objective answer for a set of values.

For instance, if we said "I would like a worldview that optimizes people not committing suicide" we could compare and contrast and say that worldview A is better than worldview B because A's adherents don't commit suicide and B's do. We can combine multiple factors, however imprecisely, and still compare A and B together as a rational person.

PG is making a similar argument in the "truth" of how art evokes subjective goods in humans. Humans across time and space are the measuring stick, and hence why the present is not overly weighted in his assessment of this evocative metric of art's quality.

PG's view on this is radical today but hasn't been for thousands of years and won't be again, because human nature doesn't change that much. Contextualization (acquired taste) can make one appreciate art better, but there is something transcendent across space and time that makes art lovely to humans, even lacking focused context.

The only relevant skill an artist can have is to capture their emotions in their work in such a way that the audience of it is made to both experience and ponder those. Extra points for complex compositions.

There is something to be said about the kind of feeling you chose to share. You can be a dick about it while stil perfecting the challange.

The white dot on canvas or the entirely white canvas are simpel displays of arrogance mixed with some prestige. Not a particularly refined combination of and it reduces to anger in many viewers. It doesnt enrich the spectators life, they know those emotions well enough which, like love songs, makes it poor taste.

There are many technically skilled artists, physicists, and entrepreneurs whose names you will never learn because the never ended up doing anything particularly original. (And of course there are many original thinkers who will never be known because they're just not technically skilled enough to execute on their vision.)

In my opinion, value in many fields ends up being the cross product of "doing the thing right" and "doing the right thing".

I think we can objectively say the da Vinci is a better painter. Or at least that his known work shows a much higher level of skill and technical competence than any known work of Banksy. That is however not at all the same as saying that da Vinci produced more interesting art than Banksy. Banksy's art is certainly easier for many to 'get' and understand and be moved by today without having to take an art history class.

And on a personal level, while I respect da Vinci as an artist more, I would still chose a Banksy over a da Vinci to have displayed in my living room (ignoring all financial arguments).