The only case I know of is the State Department's opposition to a minimum-wage increase in Haiti. And this, while I find it objectionable, was clearly done to further U.S. interests as a whole, not to favor one U.S. industry or interest group over another. It's mercantilist, but its not corrupt.
If there are indeed "mountains" of such examples, I expect that HN community should be able to come up with at least a few good examples, no? (But note: legitimate policy choices with which you happen to disagree are not necessarily evidence of corruption.)