I just checked the 20 most-recently posted questions on SO. Of the 20, 19 had no links. The one link is in Key as a variable for backbone.js model.set() and is a link to the
So, it (a) doesn't seem to be a huge problem; (b) the only link I quickly found, should definitely not be example.com.
I hit refresh and check another 14 new questions. This time, 2 links. How to change character set in Oracle 11g r2 Express edition links to Oracle documentation (again, not a candidate for example.com). How do I apply dependency injection to an abstract factory links to another question on StackOverflow.
Figuring, OK, maybe problematic links are tag-specific, I tried html. Of the most-recent ten questions (including checking previous revisions on these), none had links (though PHP/MYSQL - checking user identification from DB info thought it wise to post his MySQL username and password).
Trying again, css: There were four links in three questions (out of 10). Drop down navigation in fluid design, getting overflow when page resized linked to jsFiddle. GWT-suggestbox style linked to Google Web Toolkit docs. Linking Wufoo to an external stylesheet without SSL linked to support forums and documentation.
So, in summary, 7 out of 7 links I found should not be example.com. An example.com suggestion would have a very high false-positive rate.