The big question is - how do you tell the difference between a U.S. Census worker and a con artist? BBB offers the following advice:
• If a U.S. Census worker knocks on your door, they will have a badge, a handheld device, a Census Bureau canvas bag and a confidentiality notice. Ask to see their identification and their badge before answering their questions. However, you should never invite anyone you don’t know into your home.
There's more here. And it's a good bet I'll have more to communicate about the census another time.