I've been wondering about this for a while. Someone puts a knife up for sale, someone else says they'll buy and then a few hours, days, whatever, the knife is back up for sale. I haven't seen this with other goods, only knives. What is it with some of these guys where they say they will buy, then don't. They should be banned from the sales boards, it just ruins peoples sales/purchases.
I've bought and sold quite a few knives here and found that the regular posters are a great bunch of folks. They share a common interest and if I might generalize, they seem to share some similar values and standards. Most folks place some value in doing what they say and in doing what they think is right.
I have run into some flakes, but that is mostly from relative newcomers that usually give me a sense of being relatively young, a little cash poor, and a little irresponsible. (That makes ME sound old, but I'm not really...)
I can tell you that this community is far better than the crazies that populate Ebay sometimes. I also think some of the flakiness comes from the Internet as a barrier. I've sold a handful of things on Craigslist and the people I've met are almost universally very nice in person.