an interesting question!
a) I gusti delle persone sono diversi. (kind of explanation)
b) Ognuno ha i suoi gusti ! (like a reminders, if needs arise)
c) We use a Latin quoting, I really like:
'' De gustibus non est disputandum ''
with the meaning: you can't talk and agree upon tastes,
as they cannot change.
In Italian: dei gusti non si discute.