Well that IS one of the consequences of dating online - the person will almost never be what you expect. That isn't always BAD, just, they will be different. This is also true of any other form of dating with the exception of *looks*. When you meet someone in person, you know what they look like, but know almost nothing else about them.
I learned from experience a number of things. One is you must expect some dates you'd rather not go on. Consider them "experience". Chances are good that if you are considering the online scene, you're probably a little out of practice and it would be good to at least LEARN some things about *you* for future reference.
But another - if you are a *guy* you will have to be very aggressive in getting and setting up dates, because the women will usually not come to you. You will have to talk to many people, very often, and apply yourself. You'll write a lot of letters and unfortunately repeat a lot of things about yourself. You'll have to almost make it a hobby of sorts. If you're a woman, well, GETTING responses will be no problem. Sifting through the nuts and the married guys is your task.