Slushing is one of the most bitched-about parts of the publishing industry. People hate it and yet they also seem to love it, since so many people do it!
If it weren't for the brave slush-keepers, we'd be forced to read more unproofed, unedited, and confusing stories, so I for one am pleased to have these people doing their jobs! Slushing is also one of the more illuminating roles in the publishing industry, where you can have a close up view of what is actually being sent into markets. You may not get paid, but you do learn a lot.
This article has some great pictures, and also has some sample texts to look at.
Confessions of a Slush Reader: Why Should I Care? :: Shimmer