Let's start with adult friend finder (or any friend finder property):
FORGET IT. Sites like this are packed full of either phony profiles, half done profiles or similar. Many of these "sexy" dating sites will use bots and fronts to lure you from being a free member to being a paid member, and those profiles will disappear as soon as you sign up Basically, you will get plenty of "interested, let's chat" messages, that require you sign up. As soon as your card is run, the messages stop cold, because the girls aren't real.
Eharmony seems to have a slightly better reputation, but from what I can see (even on their commercials) they are matching up people who might not have a hope otherwise. The people who win (ie, find a mate) will crow from the top of the hills, but the failures often don't say much - and I am sure there are plenty more failures than successes.
None of these sites will publish real results, I am guessing that less than 5% of customers find anything at all, and less than 1% actually get you anywhere.
Your odds are better sitting on a street corner with a sign, I think.
Want to meet people? Join a gym, play sports, go out with your friends, have a real life. The right person will just walk in when you least expect them to.