Here's my take on this, from the single male side of things.
I try to avoid cheaters. It's a moral thing, but I also would like to avoid having a gun in my face, or being involved in some legal brouhaha.
My first potential cheating encounter occurred in 2002/2003 (I first dipped my toes into the lifestyle in 2000). I had played with single females and couples at a Pgh-area club (now-defunct) and I got a call at one point from the club owners that a woman was interested in meeting me. I called her and she told me that she had visited the club and played before, but she was interested in meeting single males at the club or elsewhere on a more regular basis. Her husband had an illness which prevented him from satisfying her sexually (so she said) and she decided to look outside of her marriage for sex, although she was devoted to him. I told her that I did not like the traditional cuckold (humiliation of the husband) deal, but if she would let me talk to him and confirm that he was sexually-incapacitated and approved of her looking outside of their bedroom for sex, then I'd be interested. She said that that was NOT possible, and if I didn't agree to see her then I wouldn't know what I was missing. (Well, actually, yes, I have an idea what I might be missing.) I was going to ask her to call me after she divorced her husband, but then I thought better of it.
A year or so after that, a woman IM'd me and we had a deliciously provocative conversation. It turned out she was married...with kids...and she was interested in exploring something without her husband knowing. Bye!
In the summer of 2006 I went to a house party sponsored by Couple A at the house of Couple B. I wasn't really interested in most of the women there except the female of Couple B. I did not play with either Couple A or B. A couple of weeks later I got a phone call from the male of Couple B. He said they were interested in a first-time encounter with a single male and they picked me. (Yay for me! I had enjoyed talking to both of them and his house was a swingers-party dream: playroom basement with sex-swing, large indoor pool, outside hot tub, big deck, and private, gigantic backyard.)
I told him things we had to discuss (condoms, no means no, etc.) and just after I had decided "YES" he mentioned, "Oh, she's married to someone else, but I'm not married. Is that a problem?" Yes, for me it was a problem. I told him if I can talk to her husband about this, to get his okay on it, or if her marital situation changes, then I'd be interested. He was very pleasant about my declining their invite.
About six months later the female of the couple called me and wanted to know if I had changed my mind about meeting with her and the guy-who-was-not-her hubby. I asked her if she was still married to her husband. "Yes." And I told her that unless he was okay with it, it was "no go." She (politely) signed off.
Just my experiences.