I've been requiring all visitors attending my open houses to present a valid photo ID upon entering, no exceptions. I have FOUR identical signs leading up to the entry (so visitors have ample notice and ample opportunity to change their mind and turn-around), plus one final notice inside that says "please have your valid photo ID ready to present to me, thank you". Almost NO push-back. But as someone is approaching me, it's critical that I appear friendly, non-threatening, open, engaging, pleasant (all that important stuff) to not intimidate the visitor, similing, and ask them to SHOW me their ID. In the VERY few times I received some "resistance" or "push-back", I say "I understand it might be the 1st time someone has ask you for a photo ID upon entering an open house, and I'm happy to be your first!" If they refuse, I politely POLITELY ask them to leave. Only 2 times has someone become a bit indignant, and those standing nearby observing it have ALWAYS come to my rescue and told the uncooperative visitor "you heard the guy......LEAVE!" This photo ID requirement is a BIG hit with my sellers. It wakes them up during my listing appointment and distinguishes me from other agents, for-sure. Agent has to be VERY confident and mindful of their body language to appear in-charge and non-waivering.