I went to one at my local store last month. I came upon it accidentally, and it was very busy (I arrived around 10:30--I don't know when it started), but not a madhouse. They held it in the store, with tables set up in different areas that roughly corresponded to what was being sold in that area. Pickings were slim when I got there, but since I hadn't intended on running into a sale I didn't care. I ended up getting a nice pair of hiking boots for my daughter for about 60% off. They had been returned after the previous owner wore them once and got blisters. But blisters, IME, tend to be more user error (unless you're working with really cheap equipment) and sure enough, she's worn them a couple of times on half day hikes with no incident.

Sarah