He later came back and wanted a refund, which I refused to do. He went and got the event manager and after hearing both sides of the story, the manager refused to intervene.
I would also "seal" up a defective hard drive inside brand new packaging and put it out on the table for people to steal. Written inside under the double flap of the box was an explaination of why there was a bad hard drive in the sealed box that he had stolen. Pretty embarassing for the thief, but well worth my time and effort.
For model train stuff (I just sell excess stuff once a year) and military collectible shows (which I sell at several times a year), I've had several people come back and want a refund because they decided they didn't want it. I've always suspected in most cases they found another just like it cheaper at another table or a totally different item they wanted more and then realized they didn't have any more money left over after the purchase at my table. Beats me why anyone would think that would work. My response is always, "Hey, this isn't WalMart, there's no return counter here." That's always worked so far and nobody running those shows is going to take anyone's side of a dispute like that. Not that this has happened a lot of times, but it's happened enough to other guys I see at shows for me to have been ready for it the first time it happened to me.
I knew a guy who put some manner of GPS tracker into (non-model-train) items that were likely to be stolen from his sales table, and had big signs declaring as such. When something got stolen, he told the cops exactly where to go and that word got around fast. He also found a way to not have his Uhaul trucks stolen at hotel parking lots when he's going to big shows by putting a sign in the windows stating that a GPS unit is hidden somewhere in the truck (and it's no bluff) that will alert him immediately when it moves and that he'll have police go right to wherever it is. in transit, if stolen. Expensive, he says, but well worth the cost for peace of mind.
He will hover and hound the seller for a deal and become extremely irate if the seller does not drop his price.
If he does swaggle a deal he will immediately race home and put it on the bay for 3 or 5 times the price... (just look for the pink ruler)
Yeah, there's a guy like that locally for military shows. I never give him a deal and once he pestered me at my table, I told him that his prices are now 150% of everyone else. He screamed, "YOU CAN'T DO THAT!" And I smiled and said, "Twice the price, now. Forever." I told him it was an "@-hole tax." I refuse to sell anything to him at any price now. Drives him totally nuts.
Another Greenberg show years ago: A prospective customer was flipping tags over to see the prices when the seller suddenly went off on him with some of the filthiest language I've ever heard (and I'm an old Sailor with a terminal case of sailor mouth myself). The customer very slowly reached over and took the seller by the throat and squeezed until his tongue stuck out and said "I just wanted to see if your tongue had turned black from those words" and left. On my second pass through the hall, the seller had packed and left.
Good grief. That's a totally unacceptable response, I don't care what it said to the potential seller. No amount of rudeness merits that. I can tell you if someone did that to several of the show sellers I know (myself included), they'd likely be looking down the loaded barrel of a handgun and if they're lucky, without seeing that split second of the muzzle flash! That customer is lucky that didn't happen or the cops weren't called!
But as for the "I deserve a deal because I'm me" types, I've seen lots of them. You think model train people are cheap? Meh, rank amateurs compared to military collectors. Had a guy pull that, "Don't you know who I am?" shtick and turned out he'd written some guide book to collecting WW2 German stuff (which I'm not into). I replied, "Nope, and I don't price according to who a person is. the price is the price, period." Yeah, I do charge more for a few people I can't stand, but he got the point. He came close to being a 150%-er, too, but paid my price on the item after all.
At a railroad collector show in the late 80s, my NRHS chapter had a sales table. This guy saw a Southern RR china dish (a butter dish if I remember correctly) for sale at $1.00. He kept coming by offering 50 cents. Nope, we always replied, a buck is a deal. He kept hovering nearby and every time anyone would even touch it, he run over and have a panic attack at the chance he wouldn't get it. This kept going until the show was over and we were packing up. This manatee came waddling over with a [bleep]-eating grin, saying, "I bet you'll sell it to me for 50 cents now!" A guy in the group grabbed it, smashed it against the concrete floor, and gave the guy some choice words about annoying us all day. The look on his face was utterly priceless. All for fifty cents.
I first started buying stuff at RR collectible shows at the age of about 15 or so (I was in a NRHS chapter and would go to shows with those great guys). All the time, people would tell me "You don't have enough for that, kid," not realizing I'd saved up for half the year in some cases. Sometimes I'd buy something similar at another table, come by the "you can't afford this" table and point out I paid more for a better item elsewhere. Man, the looks on their faces. Happened all the time. Especially in this era, never assume a kid doesn't have any money. I've sold a lot of stuff to pre-teens with giant wads of bills before!
As for display stuff, my primary hobby is WW2 living history displays. I couldn't begin to mention all the insane things I've seen over the years. Couldn't count the number of times I've watched someone move the 'do not touch' sign out of the way to pick up some rare/expensive WW2 weapon. A family threw all the WW2 ammo crates out of my 1944 Jeep at an Armed Forces Day event to sit in it to eat their lunch (my do not touch display signs were scatted all over the place). They refused to get out when I told them to leave. they also refused to get out for the MP I called right over, but of course they left when told they were going to leave on foot or in the squad car and the choice was theirs. And the MP and I got the stink-eye from them because in their eyes, we were in the wrong.