It looks like some Yahoo! Search Marketing advertisers came up with a solution to view the editorial reviews of ads that were declined. I guess if you are outside of the US and your ads are rejected, you can not view the reasons for the rejection, on an ad by ad basis. One WebmasterWorld member posted that, in order to view those explainations you need to do as follows;
(1) Log into your account (2) Click on the 'edit profile' in the 'account' tab. (3) Select 'English(UK)' (4) Then check your editorial status.
Forum discussion at WebmasterWorld.