I could have a laundry list of the SS that I encountered this past weekend at my church's yard sale, but I'll keep the list short.
First off, let me explain how my church does its yard sale. We have what we call a "Priceless" yard sale, where parishoners bring their items, set them up on tables on the church lawn (right by the road that goes in front of the church, so as to increase traffic), but we don't price anything. We ask people what they are willing to pay and then (hopefully) come to an agreement on the price. There is a central table to pay, so shoppers can buy from multiple people and only pay once. Generally, people run their own table and agree to prices only for their merchandise. All proceeds go to the church, no person gets a monetary compensation for the items they bring to the sale. We try to get good prices for the items, as the church could use the money.
1st SS: My tables (I had 5!) were completely full with baby/toddler toys and books. I had 2 full tables of Little People sets - all were new looking and complete - I had gone through all of them, matched up what figures came with each set, put them in a ziploc bag and taped the bag to the building (barn, house, etc.). I had one man pick up the barn, which had 7 animals plus a farmer, and offer $1. I said, no, I needed at least $4 (this is an item that retails for $25, mine had been gently used by 1 child and looked brand new). He made a derogatory comment about my prices being too high and put it down. He then picked up a plastic semi-hauler (for toy cars - this was Big Mac from Cars, if you recognize it) and offered me a quarter. I said No, I'd like at least $2 (retailed for $13 or so, kid barely ever touched it). He put it down and picked up a wooden train (engine and 2 cars) that was still in its packaging - never opened. He offered me a quarter for that as well. Again, I asked for $2, he put it down (this was a Thomas brand train, goes for at least $20 in the store). I saw him later with the semi and train walking to his car. I went to the cashier's table and asked what he paid, because we hadn't come to an agreement on the price. The woman at the table said $1 and he told her that I said it was ok! What a low-life, basically stealing money from a church!
SS2: A woman was looking at the items on all the tables, and eventually came up to the cashier's table with a toy car (kind of like the batmobile, with several figures all together), 5 baby board books and a rattle and asked how much it would be. We asked her to make us an offer, what she felt it would be worth. Her response: "I don't have any money on me". Who comes to a yard sale with no money? We all kind of looked at her and she asked if we would give it to her. When we said no, she said she'd go look in her car to see what she had. She came back with change and asked us if we'd take $1.33 for all of it. Everyone looked at me (since it was my stuff) and I gently said that I was sorry, but I couldn't let the car go for that. She was welcome to the books (I was selling those for $.25 each, usually) and the rattle, but I knew that someone would give us a couple of bucks for the car and I felt it was my duty to get as good of a price as I could for the church. Luckily, she didn't argue and took the books and the rattle and left.
This is why I'm not a fan of not putting prices on items at the yard sale, but I understand why we don't. If people had to price their items, we would get a lot less items donated to the sale because it takes so much extra work. Doing it this way, people gather their items, work the sale (if they want) which runs from 8am - 1pm and their work is done. Pricing stuff can take hours and some people just don't want to deal with the hassle.