I'm married but . . .
Now this one is tricky. Many of the people here are married and looking for something extra and I can't condemn that. I'm married, but my wife understands that I'm not-nor could ever be-sexually monogamous. I was upfront about that when we met and it's proved to be not only accepted, but in some cases a hell of a lot of fun.

What I'm talking about is the promise guy. I'm married but I'm leaving her next month/year/decade. Yeah suuuure you are buddy. Now I'm sure that there are guys out there who really are leaving their wives, but at some point you have to ask yourself if you want to be the "other woman" for the rest of your life.
I'll be adding to this as I think of things and I invite anyone else to do so as well.