I see a few threads offering domains for sale with very suspicious backgrounds. Domains with ZERO backlinks and less than a month old with Page Rank of 3. Check backlinks here: https://siteexplorer.search.yahoo.com/mysites Check the TRUE Page Rank here: http://www.seomoves.org/blog/tools/google-pagerank-checker/ Don't give your money to a scammer.
Domain with zero/less backlinks and less than 1 month olds is called as a dropped domain. And all the dropped domain seller always stated it at their thread, so you need learn the differents of valid, forget, and dropped domain before give any warning to other domainer here, because its sounds like you judge that the dropped domain seller is scammer, and its not true. And I'm sure, a lot of domain buyer here is more understand this terms than you
If the domains are not dropped then the pr can be due to backlinks that have been bought and i think the backlinks have not been indexed by the tool that you are using now any 1 can increase pagerank easily just buy links from high pr sites in the linksales section and in the next google update you have a nice Pr
and http://www.seomoves.org/blog/tools/google-pagerank-checker/ cannot show you the correct pr either! i usually use checkpagerank dot net