Earlier quoted context omitted.
Having owned a bar in the past I can tell you right now the most wealthy people either didn't tip at all or very little. Fellow service industry people tipped the best.
How can you tell? Most wealthy people - in my experience - don't dress the part.
My experience was that wealth doesn't seem to matter much for tipping. When I first started I always hoped for the order to the big houses, but as I gained experience I realized it really doesn't matter. Some wealthy people gave generously, as did many poorer people. One of my favorite customers was an illegal immigrant living in a trailer park. Every time I delivered it was a $5 tip (which in those days was a great tip). On a side note, when an order for this guy came up I always made sure the cooks did a great job, and I took his order first.