"Are you saying the GAO has no credibility?"
No, I am saying that when they offer their OPINIONS, they should be treated as such and not as "desh FACTS". Also, when they comment on a VAGUE report that does not provide any data to back up their claims, it does not distinguish between gross profits and net, it does not distinguish WHICH years between 2001-2003 the companies had this occur (unless it was all three, then it is obvious), it does not show what the so called "rebates" were for.... so yes, they lack credibility when they state their opinions on topics that are so blatently vague.
Also, the GAO accountants are not economists and typically not even the best accountants. Bottom line, I am not saying they have no credibility, but Desh trots them out as the be all end all and that their OPINIONS (which is what she tends to post) are not FACT.