Well let's see, people who tell you to reserve 300 bales for them (and never show), people who say they will help load or unload it and are no shows, people who don't have the money ("I left my wallet at home"), people who swear the check will be good someday, people who show up drunk ("got any cold beer?"), people who show up with friends who are just scouting for stuff to steal, people whose truck won't hold 20 bales because of all the tires, toolboxes, old hot water tanks, and a generator (???) in the back, people who's stupid kids get a sliver in their pinky and need emergency room help, people who argue over who got their first, people who show up with a copy of a Craigslist ad and demand a lower price (The ad indicates 3 year old hay). And that was just this year.
Fortunately, I tend to have a lot of fun with them, especially when I do the math for number of bales times price per bale.
Have not had any counterfeit money yet, but there are still a few weeks yet to go this year...