I agree that electronics are the worst thing to buy. If they were in decent condition, the sellers wouldn't be putting them out at a garage sale. They would try to sell them on Ebay or Craigslist first. Putting something out at a garage sale is the last ditch effort to get rid of it.
Most likely not but I don't think that's always the case. Unless I'm alone in this, it has nothing to do with condition. If I hadn't got desperate and sold my games to the record shop, I probably would have tried to sell them at the yard sale. Selling online especially on Ebay is a huge competition and I'm terrible at competitions. You have to have certain items for someone to buy on Craigslist and with Ebay, you have to worry about scam buyers.