I have been refused at Circuit City, but I was told that they would price-match it if I was a member and could show my member card. Fortunately, the place was BJ's wholesale club, which WILL sel to the public for a slightly higher price if you print out the 1-day pass on the website. It was still a good deal to pricematch to.
Now, as far as advertisements go, READ THE POLICY. Neither Best Buy nor Circuit City requires an ad. Who ever said that? Obviously, it's easier with an ad, but they still have to confirm stock. They can confirm the price at the same time (assuming the competitor store employee that answers the phone is competent... I've been refused for this).
Circuit City refused to pricematch Big Lots because their policy does not consider them a competitor and they do not pricematch clearances or closeouts (Big Lots is known as "The Closeout Store").
I suggest reading the policy for other reasons: Best Buy's policy is quite clear - you get an extra 10% of the price difference if you buy it first then return for a pricematch. MAKE SURE YOU REQUEST IT (It isn't automatic). Circuit City always does 110% of the difference whether refunding with the 30-day price guarantee or purchasing with an initial pricematch. Fry's will only do a 110% pricematch if the competitor you are pricmatching to has a similar 110% policy.