In the past I was on a site (I don't know if one is allowed to mention it, as it isn't a punting site or adultwork type thing either) where you meet people who are married or not but only want sex or flings. I actually met a few people there and had sex with them. As a male you do have to pay to read mail from people who you haven't spoken to before, or to send an initiation email to a new person, but you don't have to pay to read to full female members. If I remember it correctly, that is.
Anyway, the thing was a) 1 in 3 new mails obviously very fake b) some of the women there had a low view of men and the demand got to their heads so they were really up themselves. Some nutters 3) you don't know until you meet them what they are really like etc. 4) it seems, based on my experience of meeting about 6 or seven women there, that most are women who are married but know their partner is having an affair so feel free to do so too. Or they have comfortable conservative lives and want really dirty stuff that their partner won't do ( the proportion that asked for anal, facials, and bondage was high). It is worth pointing out that I am youngish and in very good shape, so they might be going for looks. The age spread I met was from 21 to 40 (the 40 year old was reeeeally something...unreal. In a good way). And if I am going to swallow my pride and be honest, I stopped seeing the 40 year old as I just didn't have the energy to keep up. There is a limit to the number of times you can pound someone in the arse before you get exhausted and tired of it. Frankly, you are definitely a piece of (hard) meat to them.
Some were sad frankly. In addition to the above, I met two women who were in sad situations. One was mid twenties and she was in a loveless marriage and had a child. Married to the best friend but mutually no love and no sex..staying together for convenience for both and the child. The other was a woman who knew her husband had affairs with men and women, so she hadn't had sex with him in several years "not even on birthdays". She just wanted to be made to feel like a sex goddess, and fucks nasty...with no commitments and at her convenience. She said otherwise, but it was clear she had hoped her husband would find out, be jealous and drop the rest to be the one hanging out of her.
My experiences there definitely taught me that I am very vanilla, and fuck buddies have big downsides. It is not the fun it may sound.