Dining Etiquette? Does it Exist?

The other day Madelene and I stopped off at this restaurant and bar to have a glass of wine. I was having some sort of anxiety attack, so we stopped in just for a bit. It had to be almost dinner time and the restaurant was preparing for its normal crowd to come flooding in. We sat at the bar and decided to also have an appetizer. Maybe it's because I don't pay attention enough or maybe it's just that people sometimes annoy the hell out of me, but this man sitting near us was eating his late lunch/early dinner, but so loudly that I wanted to vomit. From slurping, to smacking his lips and even grunting while shoveling a pile of mashed potatoes into his mouth. He was also eating a lot of his food with his bare hands getting gravy all over his shirt. At the end of his dinner, he was scraping his plate so loudly that I shot him a look. It was like scratching nails on a chalkboard. I'm thinking to myself, does he even know how rude he's being or am I just overly sensi...