Writing: How do you know when a scene has to be rewritten?

What makes a scene "not work" for you so that you feel you have to rewrite it/tear it apart (rather than wordsmith)?


This question is so excellent because it is so hard.

The short answer is: I just know.


The medium answer is:

I feel uncomfortable with it (see: "I just know" above) because:

the rhythm feels wrong when I re-read it. The rhythm of a scene should flow smoothly and inevitably for however you are defining inevitability -- you should never catch or stumble over the flow of action and c...