I personally only think it's rude when you get the food and put it on before you even try it. It's disrespectful to the chef that you wouldn't even give his original recipe a chance. But then again maybe you're aiming for high blood pressure.
I salt stuff, probably because I grew up eating heavily salted things cooked by my father. I could care less what people think. I ususally salt it after I try a bite...but sometimes if you salt before, it is because you just know people don't season the way you would like. My one grandmother would carry around her own homemade hot sauce in her purse, because she KNEW that no one liked stuff as hot as she did. According to my gerontology class, you start losing taste buds around the age of 50. And by 80, they are pretty much shot. (That could explain why my other grandmother dumps a cup of sugar into a can of vegetables.) Some say smokers tend to need more salt. To each his own.