Remember that it's not your job, it's the employer's job. You're just trading your services for their money and you can *always* walk away at any time and for any reason.
Please note that I didn't say that it was *easy* to walk away (try finding an employer that doesn't run credit checks and drug tests as a part of the screening process, for instance) but that option is always there.
I understand some information needed. This thread is about going too far and what they will want next.