As many have said, whether going to work while sick is rude depends on the situation.
In my current job, it would be quite inconsiderate for me to come in while sick. My boss is very flexible, and nothing I do is so important that I can't reschedule it (or finish it from home).
However, I did work for a cell phone company that counted sick days against you. I had sick days, and I had vacation days. However, if I took a sick day (or vacation day) it counted as a mark against me. Too many marks, and you get fired. The stupid thing was that if you used all of the sick days and vacation days that you were "allowed," you would have been fired before you got through half of them. (For example, say we had 5 sick days per year and 5 vacation days per year, but you were only allowed 6 marks before you were fired. Makes tons of sense...)
In that type of case, I blame the company.