Let me start out by saying that I love my wife. She is the kind of woman that I can wake up to everyday and be amazed at my good fortune. In eight years of marriage we have had only one major "fight" and maybe two minor disagreements. We are best friends and get along like few couples I know.
I should also say that I am a peace keeper to a fault. I am terrible at confrontation. I have a very long fuse and sometimes I let things fester too long before stepping up and dealing with them. My friends consider me laid back - I consider myself a little slow

With disclaimers out of the way, I do have an issue that I would be extremely grateful if someone could give me insight.
We have four kids who do not live with us. She has a 29-year-old son, I have a 22-year-old daughter, and two sons, 16 and 13. And basically she treats them very unequal.
An example would be (and there are lots) cleanliness. When her son visits, his "stuff" goes into a chair in the dining room - and no matter how long he stays it sits right there in a pile. He doesn't shower and sleeps in his dirty clothes on the couch (even after doing some yard work we hired him to do). He is admittedly an alcoholic, but I have always considered him a good kid and a friend.
But when my kids visit, if one thing is out of place (i.e. not put away neatly in the guest room) she notices and makes it a point to mention it. I can't help but think that she actually looks for things to complain about when they are here.
On their last visit, on their first day, a single sock was left on the stairs. Before saying hello to me, she noticed the sock, pointed it out, and so started the visit.
I could give example after example, but I don't want to make her look bad with only one side of the story. She is in every way a beautiful, perfect woman, but my fuse is burning short on this issue and I have no idea how to deal with it. I walk on eggshells when they are here and do everything that I can to make sure everything is perfect when she comes home.
But this morning, when I pulled out a skillet to make breakfast, I mentioned that it was still dirty (our dishwasher is getting old and probably needs a good cleaning). Immediately she blamed my daughter who is living with us now. But I know it was a pan that I used, that I washed, that I put away. I explained this to her, but it was still very revealing.
I am not angry with her (yet) and I want to keep it that way. I am hoping that someone can offer some advice on how I can help things be more equitable.
Thanks to anyone who takes the time to read this.
Just Some Dad