Rick,

Excellent observation.   Just 'one' more good reason I don't take on any new clients anymore.  It's been several years since I asked a client to provide any extra documentation.

And my engagement letter plus the questionnaire specific asks  * you have proof, right? for any of those situations.

UNLESS, they are with the fire department, or maybe the kids of long-term clients.   

I often answer to the DD question - "personally known" .