Most writers check their traditional book contracts for the advance, the payout, and the due dates. They don’t look at anything else. Writer after writer, and editor after editor, have told me this.
I always look toward the editing clauses first. Because if they’re ugly, the rest of the contract usually is as well.
This applies to all kinds of writing for traditional markets, especially for nonfiction and short fiction. I’ve seen terrible editing clauses in those contracts, and what’s ironic is that those clauses often seem to be the most innocuous.
What you want is complete control of the content of your work.