Does the other person have an adavantage knowing your faults

I would have to say they have an advantage. That's exactly how the OM got in with my wife. She told him everything about me and our problems. She thought by mentioning an issue a few times to me, she was telling me her problems. She poured her heart out to him instead of me and that's how he got her. He even told her I was a good husband and meant well. Is that hilarious or what?

As someone who was married to a serial cheater. Yes. he would listen to what women said and change his personality to fit the one he was trying to sucker in.

With me he was this strong get things done person. With this last one he suddenly became very religious. I don't think the man has ever set foot in a church. He takes on the personality of the one he is persuing.

But not everyone is my ex and there has to be a problem there before he can try to work his "magic."

I guess what irritated me the most about my stbx's affair was that she had confided all of our problems in the OM and, at first, sought advice on how to "fix" them.  Evidently, the advice wasn't sound, and she eventually gave up on us and entered into a physical affair.  I guess that was the biggest thing for me...she told everyone and their brother in her life what our problems were, but she didn't tell ME!  She assumed that since the problem was evident to her, that I should have seen it.  She got validation from everyone else that she talked to that, yes, I was the problem and that she was the victim.

I'm not saying I didn't have my faults in this and that I didn't contribute to the problems, but she had an obligation to tell ME about the problems she was having and NOT to go and tell, of all people, her LOVER what OUR issues were!!! 

So, yes, in a way, I agree with you...they get validation from their lovers and other people in their lives when they pour their hearts out to them about how bad their spouse is...the OM/OW is only interested in getting laid, so of course they're going to agree with them to get into their pants/skirt!!!  And yes, I think it does give them a sense of moral superiority in that they don't think they're at any kind of fault in the marital problems, so they can justify the affair in their own minds and avoid any feelings of guilt.

I don't think it works though...my stbx has been having problems sleeping ever since I found out about the first affair...I believe that's her guilty conscience talking there.  Now that I'm not worried about saving our marriage anymore, I have no problems sleeping at night...my conscience is clear.

I don't think it matters.  Your spouse cheated on you, I'd be more upset with my spouse for violating our trust.  I've never understood why the OMOW gets any blame, I'd be thanking them. 

Ooooohhhhh! I so hope this to be true. I believe it to be true. I know this is what happened to me. My ex met the OW and immediately grew an emotional attachment with her. She very early on used that to her advantage. I know this for a fact. Very early on, my ex and I were still talking regularly as friends, and he stated that she was being very nosy and asking all sorts of questions about our relationship. As a female, I know her game and she was only doing that to know what to do to get him wrapped around her little finger and it worked. His dumba** was to blind to see it, or didn't want to see it. I do think the infatuation will wear off with them, and I don't know if they will make it. If they do its only because my ex doesn't want to look like a fool. 

So yes they do have an advantage to know our faults. They are using our faults to take advantage of the situation
I don't know how long the OW/OM think they can keep up their manipulating facade. At some point it has to wear off. And at some point when the infatuation wears off, our exes will see the truth, but yes, usually it is to late.

I think you could be correct in that assumption, however, it's an advantage your spouse has handed them! Whatever information the OM/OW has, came from the one seeking out someone or something else in their lives.