De gustibus non est disputandum

This is a Latin maxim meaning "In matters of taste, there can be no disputes" (literally, "There must not be debate concerning tastes.")

The implication is that everyone's personal preferences are merely subjective opinions that cannot be "right" or "wrong", so they should never be argued about as if they were.

This phrase is famously misquoted in Act I of Anton Chekhov's play The Seagull. The character Shamrayev conflates it with the phrase de mortuis nil nisi bonum (in the alternate form: de mortuis, aut bene aut nihil – "of the dead, either [speak] good or [say] nothing"), resulting in "de gustibus aut bene, aut nihil", "Let nothing be said of taste but what is good".