Just butting in here as I think I may have been the person mentioned earlier who had a bad experience with swinging last year.
Basically I have always had a huge fantasy about being with another women and also about watching my husband with another woman.
We talked about it lots (I only mentioned it about 6 years into our relationship!) and decided to try a swinging club in London. We turned up and it looked like an office from the outside but inside it was done up into lots of different rooms (the main being a bar then there was a corridor with lots of different rooms off it with big beds - things like a dungeon and a bed in a cage). We didn't do anything that night we just watched others. There was a mixture of ages but there were some very good looking 20 and 30 something people there which surprised me. When we got home that night we were at it for hours!
We decided after that to try a threesome and got talking with a girl on a website called SDC (which is a good way of finding partners for this sort of thing). We talked to her lots and she seemed lovely so we went to meet her. We had drinks with her near her house then went back with her. I quite enjoyed that experience to be honest.
After that we went back to another swinging club. This ended up somehow with a 5 girl orgy I ended up walking out of this when another girl was rough with me and made me bleed. I was very upset and my husband took me home.
After that I was not keen on trying things again. I had found the swinging clubs a bit awkward and creepy personally and also found the fantasy of threesomes and seeing my DH with another woman did not match the fantasy. It did not cause problems in our relationship but I can see how easily it could for so many other people.
The reason it went so badly wrong for me was that a month later I suddenly felt very unwell with bad lower abdominal pains and a terrible fever. I went to my GP who told me I had a bad infection in my womb and gave me antibiotics. He also did a swab and it came back a week later that I had gonorrhea which it soon turned out I had passed on to DH (or vice versa we will never know). We used condoms in all encounters but I was not aware how easily this STD was passed on (it can just sit on the pubic hair). The whole thing was very painful and humilitating (lots of trips to the STD clinic, several antibiotics as we had caught a resistant strain, my doctors sympathy as he assumed my husband had cheated on me and I was too ashamed to correct him) and I have no idea to this day how badly that infection damaged me internally. I suppose it is lucky that our family is already complete but it still made me feel 'tainted' almost.
Anyway I am not against swingers and swinging clubs. I think everyone has the right to behave however they wish sexually as long as all parties are consenting. Some people just like different and dirtier things than others . It is not for me and I will stick to the fantasy from now on.
I would say you only live once and if it is something you really want to do then go for it. But be bloody careful and get yourself screened on a regular basis so if you did catch something it can be sorted out quickly. I think it can be a bit of a dangerous game but then so is skydiving....