I have found both mistakes and accurate info on the census. The whole key is finding enough evidence to support or discredit what is listed on the census. Just for example my Indian ancestors are listed Indian in Mexican records and listed as white on the US side. My DNA supports the the Mexico Indian records and my family is very dark so we know what the truth is. Why they were listed as white from Mexico on the USA side? Was this the census takers Idea or did my ancestors deny they were Indian who knows?