That's because you aren't using a page rank checker that shows if it's fake or not. Another way to test it is by going to google.com and typing in info:domain name, so it would be like this: info:fortworthstockyards.biz If it shows a different domain, it has fake PR. It shows (fortworthstockyards.org), the .org version instead of .biz, so it's fake.
Because it does have a PR 6, but it's fake. It got it's PR because it was directed to another site that has PR 6.