Maybe it's just me, but why is it everywhere I go to eat a nice meal
there is a host who obliviously serves up pie or cake by slicing,
burying their fingers in the topping to move the piece, then sucking on
their fingers and serving up the next slice? Seems to be common among
the over-50 crowd, of which I am not.

I know chefs in restaurants taste and touch food as a matter of course,
but at least they don't generally do it in plain sight of their guests
with a dim-witted sort of glee.

How do you politely tell someone, especially a relative or in-law, to
first not bury their fingers in your frosting, and then second stop
licking their damn fingers before they touch and serve your slice?