Never find fault with food. The Prophet ﷺ “never criticized any food at all: if he liked it he ate it, and if he disliked it he simply left it.” (al-Bukhārī & Muslim). He would decline politely without belittling what was offered.
العربية: عن أبي هريرة رضي الله عنه قال: «ما عاب النبيّ ﷺ طعامًا قط، إن اشتهاه أكله، وإن كرهه تركه». (البخاري ومسلم).
Don't complain about food served to you — if you like it, eat; if not, leave it quietly; never disparage it.