Good question. Could be you have too much experience and managers fear you will get bored with the job after short period of time and leave. Your level of experience could also place you outside the pay range they're offering. It's better to address these issues up front on a cover letter or somewhere on your resume to let the decision makers know you're open to negotiate.

If you are looking at jobs that pay less than what you make now some employers will disqualify you. They don't want to be that temp job as you keep looking for a higher paying position.