Here's a typical conversation I might have with myself:
"Okay, self, I know this scene doesn't exactly fit with the rest of the story. Adele really isn't staying in character when she collects ceramic rabbits. But, it is really neat that they all shatter when the Northridge quake hits, isn't it?"
"Wait, self! What if it is in character? What if the reason Adele collects ceramic rabbits is because rabbits symbolize fertility and Adele has always wanted to have a child--which is why she's so in love with Ivan, who is so much younger than her."
"Come on, self. Is that really in the story?"
"No, but one could interpret it that way if one really wanted. It still makes sense. So let's keep the rabbits. They become cool symbols!"
"Sounds good to me!"
"You're the best. I love you."
Maybe you aren't wrestling with rabbits. But, it could be anything: eels, monarchs, horses, steam engines, or even eels.
Writers tend to be smart people. For stories to work, a logical thread needs to exist that connects one idea to another, one scene to another. Often as we write, we are perfectly aware of that thread, and yet sometimes we deviate from it because we are excited about a particular new detail or a new scene. When we revise, chances are, we'll pick up on this deviation. And, in the best of times, we'll fix the problem. But, sometimes, our logic and our powers of persuasion take advantage of us--Our brain is actually having a civil war. On one side, it wants to tell that perfect, focused story. On the other side, it wants to keep the cool scenes, even if they don't really fit. Or, it's too lazy to fix a problem it knows exist; it would rather just present a logical "what if" scenario to justify the bad writing.
And, chances are, that argument will be persuasive. We really will be able to convince ourselves that a bad scene is actually acceptable. And, if someone in a critique group should bring it up as a problem, we are well armed with the arguments to justify our decision.
Problem solved, right? Right?...Self?
At the heart of good writing is our ability to tell a compelling story. And often, the excitement of that story presents itself in the earliest drafts of our projects. When we revise, our goal should be to dig back to that initial inspiration, to sort out the precious material from all the useless dirt, to cut and polish that material until it shines like a tourmaline. And, part of that process involves being able to overhear your brain when it's plotting to convince you to do something you shouldn't really do. That involves paying attention to your internal rationalization as you're making editorial decisions so that you really understand why you're arguing with yourself in the first place.
Are you able to keep from convincing yourself that bad writing is good?