Oh yeah I forgot about all the accounts that are probably fake. Man I'm so naive.
Match.com seems to be worst for this (of the paid sites). They leave them up indefinitely unless the user decides to make their account inactive. FWIW, I met my first girlfriend on Match, so it is possible. Also, they get hacked profiles where someone just makes a profile with no preferences (first give away) and then uploads a pretty picture they got off the interwebz and sends out "winks" to random guys. These are relatively easy to spot. All in all it's not a terrible site.
As for Christian Mingle, I don't have a lot of experience on that site. I met one girl on there and she is so inexplicably wonderful that I never bothered talking to anyone else and let the subscription expire. I cannot comment on the overall female content of the site, but as far as the mechanics of the site goes, it's actually one of the better ones.
Regarding Plenty of Fish...it's free and you get what you pay for. Half of the women on there have "if you are just looking for a booty call I'm not for you" so there has to be a rather large number of creepers on there as far as men go. Unfortunately, when you throw that many creepers onto one site the women get pretty jaded pretty quickly. Then you have the ones saying they don't want to be thought of as a piece of meat, but their main profile pic has 76% of it taken up by their cleavage! There is an "intimate encounters" search option. I ran this search a few times as it is excessively hilarious. I found a one-armed woman who was married but said that her husband just didn't excite her so she was looking for something on he side. You just can't make up that sort of thing! And to top it all off, she was from Council Bluffs! One woman emailed me only to tell me that I looked like a child molester. I took a peak at her profile and there was just way too much ammunition. She made a big point of saying that she was not interested in men who were overweight. That was just pure gold because when I saw her picture I thought, 'wow, if I were an Eskimo she would make one heck of a good meal. Enough for the whole tribe!'
(I generally make a point of never making fun of overweight women because I have met too many of them who have had a heart of gold. Not to mention, I have been a chubby bloke my whole life and only now am starting to diet and exercise. I know how hard it is to loose weight, though to all you plump people out there, once you get going it gets a whole lot easier! But yeah, this woman was just way too hypocritical for me not to make fun of!)
But yeah, POF is plenty worth steering away from, unless you're looking for lulz. Any woman on there who was at least remotely serious was just as picky as one you could have found on a paid site.
I have nothing really good to say about eharmony. It costs way more than any of the others and I never had it send me any matches and I am sure as heck not going to cough up cash if I don't have some idea as to the quality up front.