Smells like a mixture of dirty ballsack, vomit and a hint of mildew thrown in.
I went to the LHBS a few days ago and got a batch of beer. As I was checking out, the gut says to me that they have a special going on, and I can get 2 packets of saflager for the price of one. I was going to use the WLP830, but the saflager is the same strain, so I figures why not save a couple bucks and the trouble of a starter?
Well, I proofed the yeast, and started noticing an odd smell, oh well yeast smells odd sometimes so I think nothing of it. The yeast looked to be alright, but not getting as active as a lot of dry yeasts. So along comes pitching temp and I take the foil off the top of the yeast and GOOD LORD, I have never smelled something so awful. It was like getting slapped by a sweaty sock filled with death. I examined it and could tell that perhaps one of the two packets I received had probably not done much at all, and appeared dead. It had been packed by the LHBS from a bulk pack, and had no date on it anywhere, so who knows what may have happened to it.
Moral of the story, never buy yeast on sale, there's probably a reason they're trying to get rid of it.