My wife and her sister did quite a few years ago. They probably interviewed and photographed at least a hundred people while she was there, and ended up talking with 2-3 with any seriousness. From the sounds of it, they still had a good time, got some refreshments, etc, but wouldn't have high hopes at all [even though they were both knock-outs at the time, actually even today]. The agencies are looking for a certain look, size, shape, which changes almost monthly. If you happen to have what they are looking for, they will refer you to an actual agency for a percentage of your paycheck.
Go and have a good time, but don't get discouraged if you're passed over the first time. My sister in law actually got some minor work her 5th time after going back every year.
