aristotle - 1:19 pm on Jun 5, 2012 (gmt 0)
If you have to pay a fee to get listed in a directory, then some might consider that to be a purchased link.
In my case, I submitted to a lot of free directories back in 2006 and 2007. Some of those directories later started charging a fee, and so it could appear now that my listings were purchased when in fact they weren't. In any case, Google should simply devalue those links, which would make it unnessary to remove the listings.