William Easterly takes on Paul Collier (and implicitly many other users of regression techniques).
Oodles of regressions were run...Oodles of control variables were tried...Sample was sliced up to get results...
Read the whole thing.
My father used to say that the third iron law of social science is that the methodology is flawed. The first iron law is "sometimes it's this way and sometimes it's that way." The second iron law is that the data are insufficient.
One of the classic critiques of econometric practice is Ed Leamer's Specification Searches, a book that I highly recommend.