I completely agree.
I met with some census takers and supervisors a few months ago, and learned quite a few things. Ethnic immigrant areas are indeed counted at about half of the actual. It doesn't matter that census data is 100% confidential, and cannot be released to IRS, INS, local zoning officer, etc., for 70 years. People are paranoid about being found out.
And here's one that breaks the stereotype. Readers might be shocked to learn that the MOST LIKELY person to skip the census is a single American woman, English speaking, and of White or African-American race, and living alone. Single or widowed women, especially in urban areas, don't want to document that they are living alone. In some areas, 66% of them skip out on the census.
If the census takers really want to get accurate information, there needs to be a policy in which landlords and Superintendants are required to identify every person in every unit. And to be told, in advance, to take a "snapshot" of their building on April 1st of the census year, because so many people come and go. Even 3 months later, it's hard to deconstruct it all.