About dissonance. If by that word you mean "pitches within a certain distance from each other played simultaneously,
then I suppose that has a fairly objective quality to it. Problem is, what is that certain distance? Is it a fourth? A third? A minor second? A tritone? Different cultures and different times within the same culture will return different answers to that question.
If you mean "a tone or chord that we expect to resolve in a certain way," B to C in a C major scale, for instance, then the conditioning implied by "we expect" means that we will get different answers, too. (I no longer feel, for instance, that the sequence C, D, E, F, G, A, B is headed strongly towards one particular pitch, though I can remember a time when I did. (I may be an alien, but I became one, then. I was born right here!))
If you mean, an unpleasant sound or (perhaps) a sound that is only pleasant if it moves quickly to another sound--a sound that if prolonged would be unpleasant, which is what Prokofiev seems to have been saying with his spice analogy (which I reject, you may imagine), then that has nothing objective to it at all.
It all comes down, again, to individual experience. If it could somehow be agreed that it should stay there (and not be turned into some quasi-scientific conclusion about the inherently inaccessible qualities of atonal music), I think we might then lay this contentious quarrel to rest.
R.I.P. dear quarrel.