When you eat out at a restaurant, don’t feel that you have to eat a lot to please the proprietor.
It’s amazing how many people have guilt feelings about spending little in a restaurant.
You don’t have to have an entree. Or a dessert. Or even a main meal if you don’t want one.
And you certainly don’t need to order anything to drink but water. Tap water.
Walk out if you are pressured to pay too much after looking at the menu.
And certainly, unless in the USA, skip the tip for poor service.
In other words, learn to be a little bit mean. That way you can leave a decent tip when you do get good service.