I finally got Super Smash Bros. Brawl last week, and it didn't work on my Wii. The Wii wouldn't even recognize that there was a disc inserted. I wrote to Nintendo and asked if that was symptomatic of the known problem of some Wii's not playing SSBB. They said it was and that I had to send the unit back for repairs -- no lens cleaning kit, not even their own, would solve the problem.
Today, I got the official Nintendo Wii Lens Cleaning Kit I preordered from Amazon back in January. I put it in, cleaned the lens and...
... SSBB plays perfectly (at least so far).
I can't guarantee that it'll work for everyone... I could be isolated case where it's just my heavy smoking that caused the game to fail. But every other game I have plays without any disc read errors at all. Who knows?
Still, I'm sold on the lens cleaning kit as a worthwhile $10 investment.