That, and the buyers who don't get back to you after asking if it's still available. Not too long ago, I had a mountain bike for sale on OfferUp. Someone was interested in it, and then I didn't hear back from him for a while. I messaged them back, and apparently they didn't get my last message, and he said he ended up buying a different bike but would have preferred mine.. Really?? I did end up selling it to someone else though.