Hape- That is a very very awful feeling. I personally don't have my kids home when interviewing. My husband takes them out for a doughnut at the tims around the corner from our house, and comes back usually within 30 - 40 minutes.
I don't allow anyone to take anything except a copy of my contract ( my husband being awesome put water marks on the paper, interviewed a person who was looking for contracts to copy for her daycare. She called two days later wanting to know how to get the watermark off. She had tried to photocopy it for her clients. I was like"Your not only going to steal my hard work, but your even going to steal my name?".), photo's ect. Parents must come with their child, and I ask if they are switching from another daycare to have a letter of progress for the dcp( lets me know how they were in daycare, any areas that are problematic ect.)