Subject is exactly blended in
Sinclair's novel on immigrant life in the US is most famous for its description of the meatpacking industry. The author interviewed workers extensively and blended in at the plants to do his research over the course of more than a month.
"Gateway to Gridlock" - Louise Kiernan, Andrew Zajac, Robert Manor, Evan Osnos, Andrew Martin, Laurie Cohen - Chicago Tribune
In this Pulitzer Prize winning series, Chicago Tribune Staff Writers reveal the issues behind the scenes at O'Hare International Airport and "why airport travel had gotten so bad." Although there is no explicit indication of the use of any subterfuge, which the Tribune no longer supports, informed readers had the sense that some of the information had to have been obtained without the professional affiliation of the reporters being known to staff.