Buying tickets online and being charged a “convenience fee” for the privilege of buying it online.
I worked in the collections department of Discover Card for a while. One thing they did (maybe still do), to lure customers to them is offer 0% APR for the first year. People would jump on this and transfer all their debt onto their new Discover Card, and then the company would “conveniently” not send the first month’s bill. In the fine print of the agreement, it states that if you miss even one payment in that first year, your APR will jump to 29.95%. Half of my calls were to these new customers who would then proceed to throw a fit, because they didn’t ever get the bill, and I had to explain to them that it was their job to know when the bill was due, and sending one was just a courtesy extended by the company. I hated hated hated that job. It ate away at my soul.
Petco will sell you non-aquatic plants specifically for your aquarium that will poison everything in the tank.
The “You won a TV / $5,000 / bass boat!” scams at car dealerships.
Generally, you get a flyer in the mail that says “scratch off x to see if you won!”
You always “win” the biggest prize but when you read the fine print, you actually only win the right to spin some wheel or put your name in a box for a drawing.
Mattress stores that have the “find it anywhere else for cheaper, you get your money back!” deal contract with the manufacturer to make the exact same model of bed, but with a model name specific to that store, so nobody can ever cash in on that deal.