Thankfully I've never really been ripped off, never been robbed...who knows, it may change.
I've been close to that, though. One time I was looking for an apartment in Toronto and came across a nice-looking ad on Craigslist. I can't remember the details clearly, but I really needed a place to stay and when I got in touch with the owner, I think he told me that he wasn't available to show me the apartment, but if I sent him money via Western Union he'd get someone to give me the keys. Something real fishy.
I was naive enough to think it might work so I went to a store with a Western Union outlet, not feeling good about it, and called their support line when I got to the kiosk. I asked the lady on the phone if she thought it was a scam and she said, "I don't think it's a scam, I know its a scam," and so obviously I didn't go through with it.
The kicker was, when I was on the subway outside, I got a call from the guy asking me if I had sent the money yet. I blew up at him on the phone telling him that I knew it was a scam and he hung up immediately.
Another weird story - my first time in NYC when I was 20, I was walking around solo at night and a guy with his friend came up to me asking if he could borrow some money. I only had a few dollars left and needed to save as much as I could. He told me it was his birthday and kept asking. I caved in and gave him some. I guess incessant begging is kind of a hustle.