Compared to many other stores, Wal-Mart seems pretty light on the advertising. I only get Sunday ads for them about once a month instead of every week like other major (and not so major) stores in the area. They don't even seem to have that many commercials compared to other retailers.
Hmmm, I think that 99% of Americans would recognize the Wal-Mart smiley-face logo. Their marketing is very effective, regardless of whether they buy ads in your paper or on TV.
Marketing is not the same as advertising.