A few questions to ask yourself...
Why are you putting that in your painting?
What should you be taking out of your painting?
I've been doing some writing lately, and the deal with good writing is that it seems to go hand in hand with good editing. I have a tendency to over-explain, and a good twenty percent or more of what I write turns out to be unnecessary and gets edited out in the final draft - if I am doing a good job of editing myself, that is!
A good painting can become a great painting with the right editing. I'm currently playing with a little piece featuring a cluster of saskatoon berries (ever heard of saskatoons?) and there was a leaf dead centre of the reference photo. As I sketched my composition, I was about to sketch that leaf when I asked myself WHY I would be putting it in. "Because it's in the reference photo" is not a good enough reason. So I omitted it. Unfortunately, I didn't think to edit another portion of the photo and the painting has turned into more of an exercise than anything I could frame or sell.
Editing is important. Every part of your painting should be the way it is for a reason. I'm not good at this yet and it's a real strain on my thought processes to be deliberate in what I paint, what I omit, and what value and colour temperature each stroke should be. I've been studying some of the great paintings and when I look at their work, I look at it with the idea that every stroke in the painting has a purpose - it's amazing how their work comes alive when I consider this.
To use one more illustration - when I watch a suspenseful movie, I listen carefully to the dialogue, knowing that it was scripted for a reason. Stuff that sounds off-topic is going to fall together - an important piece of the tapestry that is the storyline.
Which is why it still bugs me that I painted in that fire hydrant. Dead centre of the painting, too!