Question about fake page rank checkers

I was going to buy a domain on ebay. Pr3 or 4 just to save time. I assumed these names would be snapped up off drop lists and resold. A friend told me to google "fake page rank checker" and try them. 3 of the 4 domains I Was looking up showed as fake on all the checkers, 1 was thought to be real by 1 checker and fake by 2 others. Whats the deal with these checkers? Are they right?

 

I would recommend digpagerank.com. If it's not green, don't buy it.

 

try checking at www.pagerankz.net also.