what you say is true, but i think your haircut example just glides over the more important question of what we can actually compare objectively and what we can't.
it's true that taste varies and is culture-dependent, some people hate punk rock, others love country music, etc. but i think we tend to over-exaggerate this. after all, nobody drinks vinegar by the glass, eats rocks, or likes earing really strident sound.
there is an objective basis to taste, rooted in evolution: eg sugar is energy, we need that to live, so we like it - a lot.