NEVER LET STRANGERS IN YOUR HOUSE. Your wife is VERY lucky that her ill conceived actions have not yet had BAD consequences.
She needs to start watching the news, (every time a story comes on about home invasion, murder, robbery, rape etc. call it to her attention) Have her start watching "The Best Defense".
There is nothing you can do now about her past bad judgment except to increase your precautions. But you need to stress to her the need for AWARENESS, and that this is not the 50's any more. That type of bad judgment can get one or both of you killed.
Exit question : If he's making a living selling Insurance door to door, (does anybody REALLY still do that ?) why no contact info and why is he driving a sh!tbox vehicle ?