I think a lot depends on your local Wal-Mart/PetCo/PetsMart/etc. I would not buy fish from any of the above-mentioned stores in my area. Some people on this board have mentioned that the same stores in their areas have excellent looking tanks and fish. Depends on the manager/workers, I guess.
Personally, I don't like Wal-Mart and try to support them as little as possible (a difficult thing when one is a poor college student). I'd much rather support the LFS. Coincidentally, my LFS is the only place that I've found so far that has healthy fish and good looking tanks. I do still buy a lot of my fish supplies at Wal-Mart or similar places, mostly because of the money issue (I'm a college student, remember?), but also because Wal-Mart is three miles away from me and the LFS is almost an hour and a half away.
I'm off to get ready for a concert...
Pamela
aka Lizard