I've done online dating. With SOME success and some failures. I'm actually engaged to someone I met on a dating site. But we actually dated and got to know one another and enjoyed and looked forward to spending time together.
Having said that, I've had everything from women just wanting casual sex, to wanting money, wanting to make babies (not just sex, but sex with intent to get pregnant) on FIRST date, women who were 9 months pregnant but never mentioned it, a relationship with someone married and still living with husband (hid that well) and even met her teen kids and parents, was asked to take a woman and her son out to eat because they had no food, one asked to stay the night with me then move in (FIRST DATE!), One kept saying (I know I'm ugly, but....). One lied about her age by like 6 years (I was 35, she said 29, she was really 23, she got SMASHED drunk at a bar. It's crazy. Just...crazy.
In this busy world it IS a tool.