While this line of thought may make you feel better about living in SF, it's just not true. Having been and lived in a number of mid-to-large sized American cities, I can honestly state that SF is by far the most urine and feces covered.

If you want to see someone defecate in public, SF would be by far the #1 place to visit. You're unlikely to see that behavior tolerated in NY, Chicago, KC, Vancouver, Seattle, Portland, Sacramento, Phoenix, Denver, or any other city you'd care to mention.