Why is roadside food so yummy?

This question crosses my mind every time I eat out of these roadside food stalls outside my office building. I still am not able to figure out what makes this food so tasty.

Today I had roadside South-Indian food, and as all the roadside food is, it was really YUM!!

Of course, all the dirt and grime that goes into it makes an integral part of such food but is that all it takes to make tasty food? :-p