Michael O.Church briefly talks about this in his article on startup culture: http://michaelochurch.wordpress.com/2012/07/08/dont-waste-yo...
Also, see the recent HN post, "Ask HN: I just inherited 700K+ lines of bad PHP. Advice?": http://news.ycombinator.com/item?id=4557919
Lastly, in my article I highlight Open Office, which still has comments in German in its source code.
In our corporate environment we do enough to pass the tests, with one extra 'test' being a peer review which should take into account a list of criteria that aren't easy to check for automatically; house code style, test code coverage, future maintainability, g11n/i18n-ness, etc.
We often only go as far as 'just good enough' but the standard to which that is assessed is pretty high.