How were the real and personal property values determined for the 1870 census?

The realistic question is what instructions were given Assistant Marshalls (who were the census takers) in filling out that 1870 column.  I go to: https://usa.ipums.org/usa/voliii/inst1870.shtml  and I see :

Property.-Column 8 will contain the value of all real estate owned by the person enumerated, without any deduction on account of mortgage or other incumbrance, whether within or without the census subdivision or the country. The value meant is the full market value, known or estimated.

"Personal estate," column 9, is to be inclusive of all bonds, stocks, mortgages, notes, live stock, plate, jewels, or furniture, but exclusive of wearing apparel. No report will be made when the personal property is under $100.

However, I've never seen in census instructions the right of census takers to demand proof for the statements to questions that they may receive.  

Thanks. I had seen those instructions to the Assistant Marshals but nothing about how the Marshals were supposed to get this information. Based on your comments and also by looking at the forms, where the Marshalls go out and canvas the individual households, I am assuming the Marshalls just asked and took what they were told. I cannot imagine that the Marshalls went and looked at property tax rolls or anything to get valuations. It is no wonder that they stopped asking for this data after the 1870 census.