They were a hallmark of the U.S. housing crash: Mortgages that required little or even no documentation.

During the boom, they were called "stated income" loans, but advertised as "low-doc" or "no-doc" loans. When the damage was done, they were deemed "liar loans." Both lenders and borrowers alike would write basically anything on the mortgage application to get the deal done. Now, nearly a decade after the financial crisis began, a new version of the stated income loan is making a comeback.