I don't know how much truth there is in this from the foreigner's point of view, but a lot of us believe (me and a lot of my friends included) that a vast majority of tourists who come to India want to witness this very same upon coming here.
It also fits one of the many reasons why the density of foreigners is maximum in areas like Pahar Ganj and Old delhi (the dirtiest parts of Delhi IMO). So when some "gora" (typically white people) complains that Delhi is so dirty the biggest wtf going on in my head is.. then why the hell are you staying near Pahar ganj or traveling by a cycle rickshaw in 42 deg near Nai Sadak. The place near the Airport is cleaner than New York ( at least after the common wealth games) but nobody wants to see that. Who wants to come here all the way to see some old glass building in neat and clean surroundings. What's unique about that right?