Try it with a CCBill number and you will see it carries over fine:
http://www.beachmodel.com/free_sites...ccbill=1352409
With xxxxxxx it will not.
<input type=hidden name=ccbill_referer value='1352409'><input type=hidden name=referingURL value='http://www.beachmodel.com/free_sites/beach_girls_in_thongs/index.php?ccbill=1352409'><input type=hidden name=referingDestURL value=''>