Typically the first visit is a request to be voluntarily let in. If denied they will return with a police officer and a warrant to enter, and will be more likely to try to hurt your family rather than do a cursory walkthrough. It’s a bit of game theory but it’s best to let them in the first time.

As the story demonstrates, there could be extra-legal consequences whether one allows them in or not. For average people without very deep pockets, it's damned if you do, damned if you don't.

I denied the police officer entry. He made me produce my child (to show she was there and safe) but that was it. A CPS representative came a few days later and we were advised by a lawyer to let him in and take a look. He made some minor suggestions about cleaning up around our younger daughter’s high chair (she’d thrown some food around her chair) but nothing came of it.