Is dining etiquette common sense common?

I remember the first time my uncle took me to a very expensive restaurant for a seven course meal. The hot towels were brought to us to clean our hands; he then decided to tell me a story. Apparently, a young man called Joseph was ill advised by his friends that if he ever went to a hotel, the first thing that he was given by the waiter or waitress before making his order was to be eaten because they are called starters and they are free of charge. One that fateful day Joseph decided to go to a very expensive hotel just to eat the starters and leave before he actually makes any order. As fate would have it, at the hotel he went to, before an order is taken, they provide hot towels and then offer starters. When Joseph saw the hot steaming white thing, and the way the waiter used a thong to pick it up, he definitely thought these are the starters that his friends had talked about. He immediately took hold of the hot towel and started biting it. It was too late when he realised that it was actually a towel for cleaning his hands. Dining etiquette common sense, therefore, is not so common. There is nothing as shocking as seeing people you expect to have table manners doing the most outrageous things before or during a meal. I once saw some foreign expatriates at a hotel before having dinner using the hot towels given to them of the hands to clean their armpits instead. Honestly speaking, I was close to puking. I believe some people just need to be trained because I will forever say that etiquette is not common sense. I think I’m just unlucky but I have seen several bizarre things at restaurants and hotels. One day at a café, I saw a man drinking tea; I think he had put a lot of sugar in the tea so most of it got stuck in the cup. When he was through with the tea, he inserted one of his fingers into the cup to get the sugar and he started licking his finger. I was in total shock. Consequently before you do anything outrageous while eating at a restaurant or hotel, know that there is someone enjoying their meal so avoid making them regret your presence.