Add an anosmia status condition, in which you have no sense of smell:

• Tins cannot be identified by their smell, unless they contain spinach or are empty.
• Messages involving smell, such as when you cast stone to flesh on rocks, are suppressed.
• Food detection scrolls and the spell of detect food don’t work.
• Food appraisal doesn’t work.

Not specified what things in the game might cause this condition, or if it should be a roleplay birth option.

You can occasionally get a free food appraisal when you eat something. This is based on a random number computed from the turn and (possibly) the object ID, weighed against your Wisdom somehow, such that higher Wisdom increases the chance that you get the food appraisal.

Some roles get food appraisal as a permanent intrinsic. Caveman at level 6, Tourist at level 10, maybe Healers at level 1 but they already get poison resistance so maybe not.