Some guy walked up to me, opened his trenchcoat, and offered to sell me a Rolex! Should I buy one?
You can buy a surprisingly wide variety of merchandise, with correspondingly wide variations in quality, from street vendors in New York. The fake Rolex watches are of very poor quality and often don’t last a day. Although slightly better than the watches, the fake Oakley sunglasses are definitely not as durable as the real thing. T-shirts are very cheap, and often fall apart after the first time you wash them. It’s fun to negotiate with the street vendors so by all means do; just don’t harbor any illusions of product quality, especially in “touristy” areas like Times Square. You may be able to find some surprisingly higher-quality merchandise in Chinatown and other areas.