Years back, the house we're currently renting was for sale. The realtors informed us of blanket dates/times that the then-landlords approved. They then gave us consent waivers to sign, basically saying that we absolved them of any responsibility for missing or damaged property. We refused to sign said waivers. They protested, claiming they had legal right. Still we refused. They then asked us to be present during the posted hours, so we could ensure the safety of our stuff. We again refused, noting that we both worked for a living and could not be expected to put our jobs on hold.
In the end, they sucked it up. It seemed they became pretty selective about showing the property; there was only evidence of visitation on three days (we rigged a couple of tells on the doors so we would know.)
Someone, I STRONGLY suspect it was one of the realtors, used out ladder to climb up in the garage and remove the screw-in light sensor we had. Other than that, we didn't have any issues.