It is polite to talk with your mouth full.

It is perfectly fine to keep your elbows on the table?

Taking food from another person's plate is a okay!

Being stingy at a dinner table to the waiter is polite.

Tony has been on his phone since he sat at the dinning table. For Tony this is acceptable as he is a businessman and very busy.

Spiting back the beverage in your cup is socially acceptable.