That depends on the agreement. Some claim rights over everything, others only over things related to the company's business, or to what you personally work on. Also, various states limit such things, and if the employer overreached it could be unenforceable. I don't think it's bad faith to ignore a contract that the state says is too unfair to enforce.

My suggestion: read the contract carefully, make a list of specific questions, and spend an hour talking with a lawyer.