Though I'm new to BPL, I've been a UL backpacker for years, and I'm so grateful I've found this site and the Gear Swap section. Like other posters have previously stated, I now finally have the opportunity to experiment with gear at a fraction of the cost of buying brand new gear. I've landed a couple pieces at a discounted rate.
The OP also mentioned that sellers say items are used 1, 2, or 3 nights, and it's a frequent occurrence, maybe too frequent. Actually, doesn't it make perfect sense that most of us have to buy our UL gear sight unseen from cottage companies, then test it on an initial trip and see if it works for us?
For instance, I bought a SMD Lunar Duo 2 for my GF and I, then we broke up after we used it for one trip. So I sold it on here for a great price. I didn't want to return it to SMD, since it was a brilliant piece of gear with no defects. It's not SMDs fault I'm lousy at relationships.
It's up to us to ask questions, and ask for detailed photos. That's what I did. For the most part nowadays, if you're savvy enough to buy and sell gear on forums, you probably have a camera of some sort. I post plenty of photos, and ask for photos from all angles. Problem mostly solved.
Oh, and I also think it's up to us to make sure if a seller is consistently posting misleading ads or selling bad gear, that we make sure the BPL community is aware of that fact.
Anyway, I'm glad to be a part of the BPL community after all these years, and I thank all of the posters who post accurate, honest info. This is the type of site that makes the internet such an incredible resource.