True, because it happened to me once, in fact MORE than once. But here's ONE example: I was on a site and some nutty girl pretended to be three different girls talking to me. I was stupid enough to give her my email address. From that, she managed to find me on Google+, I think it's called, where I also had an account. Next thing I know she's demanding to Skype with me. I did, but she looked nothing like the pics she was using on the site, or how she sounded when we talked on the phone. I still can't figure the whole thing out, but she was definitely a predator.
When I tell people about it, they say, "Well, did you ever see that TV show, Catfish"? I tell them no, because I haven't, and I don't WANNA see it. I don't think I'd find it very entertaining, considering I had to deal with it myself.