Thought of another yeast I don't like: 2007, the Anheuser-Busch yeast. I always accused this yeast of throwing a lot of acetaldehyde, which accounts for the nasty green apple flavor of Budweiser. However recently I've read that it's the beechwood "aging" process that causes this. Beechwood chips are added to the fermenter to drop out the yeast before it has a chance to reduce the acetaldehyde. So it could be that the yeast is fine but their process is just broken. For now it remains on the list.
Or the acetaldehyde is a feature and not a bug. Both Budweiser and Heineken have it (Bud some, Heine tons) and I suspect to the average drinker it adds a bit of crispness. I can tolerate Budweisser but cannot stand Heineken.