Some contracts are bad. They get their hooks into the author’s copyright; they have restrictive option clauses and punitive indemnity clauses; they want to grab not just world publishing rights but the right to publish in all forms everywhere forever, including Mesopotamian baked-clay tablets and electronic transmissions to the Oort Cloud.
Other contracts are worse than bad, they’re unconscionable. They do all of the above, and they don’t do the one thing that could possibly induce a professional writer to sign them, which is to offer good money up front.
Just about every professional writer has signed at least one bad contract, and they’ve usually done it for only one reason: they needed that up-front money, and they needed it right then.
Once in a while, in this business, you may need to sign a bad contract. The roof may leak, your kid may need emergency orthodontia, the IRS may be demanding more blood than your normal turnip harvest can provide. If that’s what you have to do, then do it with your eyes open and deposit the check before it can bounce.
But nobody, ever, has any reason to sign an unconscionable contract.
Dr. Doyle's Blog 
As a self-publisher, I make my own Mesopotamian baked-clay tablets! And they’re all nice and square with clean cunieform marks! (shakes fist at those slovenly mass-market tablets!)
As a self-publisher on a shoestring, I can’t afford cuneiform tablets. I have to use quipus.