The earliest memory I have of being swindled was the video game The Yukon Trail. Early in the game while you're buying supplies to take with you to Alaska one salesman will offer to sell you two "gold-sniffing gophers" with the promise that they will help you find the best claim and where to dig on your claim. Being a naive child playing a video game I assumed that the gophers would really help and that they would be worth the steep price when I was able to bring up all of the gold in the Yukon with their help. I was heartbroken when, upon reaching the Yukon and letting my gophers out they ran off and just returned to the wild. Looking back, that is the only part of the game I remember, I even had to look up the name for this blog post, so it made and impression. I think that swindling, when used in moderation, can lead to some memorable and fun games. Plus once the players are swindled they have a natural enemy, give him powerful friends if your players are ready to kill NPCs whenever they're upset if you want to keep him around.

I don't have too much more to say on the topic, so I'll just provide a table of some random items to try to swindle your players with. I'm only about a third as creative as d4 caltrops so I'll only provide a d66, though bear doesn't like the size of the table, I will break it into lists

1

1. Gold-Sniffing Gophers (that run away)
2. A "Treasure" map (that leads to an ambush)
3. An authentic treasure map (the treasure has already been dug up)
4. A guard dog (that sleeps through the night)
5. A figure which crushed will summon a panther (but really just turns into a broken figure)
6. Magic beans (lentils)

2

1. An invitation to the king's court (an forgery that any guard will recognize as such)
2. Pilgrim's charm that will protect against bad weather (a hastily carved face in a small piece of wood)
3. Indestructible Stone, complete with demo (demo is using an already broken hammer, it's a normal rock)
4. A skeleton key that opens all locks (it's just a normal key that can open a few locks for demos)
5. A fresh, fit horse at a great price (actually belongs to the captain of the guards, he's looking for it)
6. A book on how to learn [pick a language appropriate for the setting] (it's actually complete gibberish with fake definitions)

3

1. Spices from far exotic lands (some actual spice for smelling, the rest is pigment)
2. A cowl that will make you invisible in shadows (just a normal grey cowl)
3. Potion of charisma (strong grain alcohol)
4. Potion of strength (complete with fake demo, actually just urine)
5. A charm to protect from faeries (it's just sticks bundled together, no protection)
6. A book of sword techniques from great masters (made up stuff that looks cool but is likely to get you killed in a fight)

4

1. The rights to charge toll on a local bridge (this one may work for a while, especially if they give the local government a cut, but don't forget that more copies will be sold; eventually someone with better connections/power will want to take over)
2. A holy symbol that makes you invisible to undead [only 1 available] (just a normal holy symbol, no magic)
3. An off the books jeweler who sells jewels for cheap to "avoid taxes" (use this person to sell pretty glass to adventurers who are trying to lighten up their coin purses)
4. A Digesting Duck (should be very expensive, unless it's discovered as a hoax it could be used to make money)
5. A health potion (water with red dirt in it)
6. A currency changer (using a dirty scale, takes a 10% cut of the real value, before the processing fee)

5

1. Jewel encrusted dagger (actually cursed, marking you to be haunted by the ghost of the original owner)
2. Loaded dice (demo with loaded toward 7, sleight of hand ones that trend toward snake eyes)
3. Totem of leadership over a distant nation, being sold because the trip is too hard (it's not real, any attempted coup using it will result in a nation against the party)
4. Deed to a farming estate a week away (actually owned by a local noble who will be visiting again)
5. A "genuine" painting from a dead artist of high renown (actually a forgery than any art appraiser will spot easily)
6. Their own supply of scented oils to sell to others, but the real money is in recruiting people to sell for you...

6 (Slightly Magical)

1. Pair of circlets of communication (they only work for about 30 feet of clear air)
2. Ring of invisibility (only has power for 30 seconds, enough to demo)
3. Amulet of water breathing (only works in distilled water)
4. 7 league boots (when they're far from their master they walk back when unworn overnight)
5. Pendulum of locating (will point to a thing, but only if the user knows where it is, is picturing it, and is within 10 feet)
6. A deck of cards that will allow you to draw whatever card you need (it can and will produce duplicates quite often and it cannot create new cards once 52 are drawn)

Words of caution

Use these sparingly, unless your players find these situations funny (I don't know your table, you do). When characters are getting swindled, try to make your vendor not an idiot, they need a way out if they're discovered, they shouldn't be in a permanent location (unless they have some powerful friends and allies), and when push comes to shove give them some teeth.

If your players think of clever ways to use these items reward them, don't be upset that your "haha, got you!" didn't screw them over, but be happy that they made lemonade out of lemons.

Another day, another post of ground that has been covered a lot, but hopefully it will be new to someone, and, if not, hopefully enjoyable for someone.