I was in the French Quarter in April. Bourbon Street had a noticeable stench. Sort of a watered down vomit smell. The rest of the area just smelled like big city. We stayed on Canal Street which was had no odor.
Most of downtown New Orleans lacks the “aroma” of Bourbon Street, which is sort of a historical feature of the city. In the summer, it’s easy to picture the women in upstairs rooms emptying chamber pots on the heads of occupying Union soldiers. ;-)
Mardi Gras. New Orleans is full of people who drink too much and behave badly. I’m sure that it’s much nice the rest of the year.