Parent might be referring to the fact that it can easily give false positives, but I'm not sure.
I think it's the project that does syntax highlighting for the code browser in Github?
Re:Results of the GitHub Investigation
by rurounijones on Tuesday April 22, 2014 @02:36AM
(#7626137)
It is the software the identifies % of language used in a repository and highlighting etc. https://github.com/github/linguist
I just haven't heard anything bad about it so am curious why OP calls it a "debacle"
Googling didnt bring up anything obvious,