I can't count the number of times my NYC working husband & officemates have spent quality time in the office bathroom from dining on their various local street cart lunches. Doesn't deter him or his co-workers at all. There's so many unregulated carts in NYC, that you ust have to believe it's AOK. Having lived in NYC for 10 years, I've never became sick from the hot dogs, which was the only food item I was tempted to eat.

faith in the cart owner and the Food Safety regulations that are in place to protect your health. I would say, check out how many people line up at lunchtime for any one cart... I live in Mexico where I eat street food all the time and have never gotten sick. I simply look for those that are most busy-- check them out for a few days. These folks want to stay in business, right?-- getting people sick doesn't really result in repeat customers.

If there's good turnover at lunch hour, hop in line -- everything's probably pretty fresh (and it's probably really good too). Otherwise it could be a gamble. I haven't seen letter grades from the NYC Health Department on any street carts, but that would be nice!