Sally,

You shouldn't have to do that.  It is up to you to enact policies that you feel are  appropriate to lower your liability and exposure.  Your clients must trust that you have satisfied yourself and offer a reasonable standard of care with information provided in order to complete the search.  If you breach that reasonable standard your client can always seek restitution or recourse within the court system.  

I have never been keen to the idea of a customer telling me how to run my shop.