Fake people online!

" The beauty of internet drama is that without internet it does not exist "

In this case I am not talking about scammers, spammers or perverts. I am talking about real people pretending to be someone else. While I don't mind some lies, I do mind the lies about the characteristics or personality of someone because those are the things we connect with. It is unavoidable to meet people like that online. But what should we do about it? On several occasions I have found people who weren't true in their personalities and their intentions. Since fake people can bring out real emotions it can be quite hurtful when the finally do discover. I try my best to warn when I signal someone fake. But I must say what is the correct way to proceed especially when the one you are warning isn't aware. Because I am as straightforward as you can get I simply tell it how it is. Not that I am expecting people to immediately agree with what I am telling them. I do expect people to take it seriously. But in practice it doesn't work out that way. Only few appreciate it and the rest simply ignores it until it is already too late. And therefore will probably face the consequences that could have been avoided. I did warn them! 

Edit 14-03-2013: 
How naive I was. After many, many and many experiences it is safe to say that I understand certain people a little better now. For some assuming a role is the only safe way they can get out of their comfort zone and connect with people. In a way that can be seen as a positive thing. But of course only if one does come clean in time. Or that the other one is made aware of the role play.