PR5 generally means that you are well connected to a lot of sites that may have a PR rating higher than yours or equal. It doesn't always mean a lot of traffic. My ex-boss has a site that is PR5 and gets like 20-30 uniques a day. Mine is only PR2 thus far, and gets 50-100 uniques a day. So it can be an indication the site is well connected with backlinks, but it is also fairly easy to manipulate and thus can not only give you a good picture. As someone told me, traffic and placement are more important than what rating the PR is and of course if there is income if you are selling it.