I typed in Topsites in google, on page 5 at the very bottom there is a site called www.phantomsquare.com/ which has a PR0, then on page 6 all the listings have a PR5 or 4 - how can this be or am I going a bit loco here.
it is very possible , the site you see PR-0 is ranked higher for the keyword you used , those others that are PR5 might come up better on different keywords.