Fake recips are - well - fake recips
A recip link is meant as a traffic exchange. But if there is only one link list sending traffic there is no traffic coming back - and hence it is not really an exchange.
For example I have sometimes noticed my own recip links placed neatly between Tommy's, Richards, and Tumbzillas... on
http://www.somesite.com/index37.html - heh.
Of course nobody in their right mind would submit a "index37.html" to any of the sites but mine. So I consider that fake recips. If I listed this I would be the only one sending traffic.