I had an interesting experience recently while apartment shopping. I found one I liked, and put in an application and paid a $150 security deposit, which I charged to my credit card. I then decided on another apartment, and canceled my first application. However, the charge on my credit card was not cancelled and instead I received a check of the full value.
This means I spent $0 and received $0.15 from the credit card company is points. What's to stop me from repeatedly doing this? For example, why can't I go to my friend's business, buy $10,000 from him/her, then get a refund by check?