Conditions are extremely crowded - beggars and others are up touching you on the arm before you know it. At train stations and on the street, you're jostled with all kinds of people.
Animals run free everywhere.
The city water is often not safe. The air quality is extremely poor. Because of these conditions, I won't take an infant to India. My child would have to be at least 1 year - more like 2 to 3 years old to give it time to develop more of an immune system. In general, I don't want to vaccinate, but visiting India every few years makes me wonder.