If "location, location, location" is the mantra of real estate, "content, content, content" would be the equivalent for online dating. What a person says and how they say it, speak volumes about who they are and not just who they are trying to make you believe they are.
Some people are better at faking how kind or genuine they are. But with a little time, people eventually can't keep up the charade and their pretend self cracks revealing who they really are. Hopefully you find this out LONG before you ever meet in person.
Case in point: (click on the picture to enlarge it.)
It took a little while, but after a while, the "sweet guy" act fell by the wayside and he got angry and bitter in a hurry. I still have no idea what triggered it. Anyone have any theories?