9 out of 10 people I meet on craigslist are hard working honest people. There are always those few who are just idiots. I've had a guy not show up then call me the next day saying he decided to go to his GFs house instead and forgot to call. He wanted to meet up the next day, but I said no. I waited for him for 30 minutes and he never showed, I wasn't going to waste my gas again.
I agree that 9 out of 10 of the people you actually meet (in person, during transaction) are hard working and good to deal with, but 9 out of 10 people who inquire about an item are the opposite.
I should say I had a great dealing yesterday on a bike. The guy came down $50 on the price, threw in a bunch of extras, and met me halfway right on time.