I understand why businesses offer money-back guarantees, but as a consumer I'm not really a fan. I don't want my money back. I want your product to work the way you say it should work. That said, I will still take my money back as an alternative to holding a product that does not work.
Some people call it a risk-free trial, but there is no such thing. There is always a risk. There is a risk you will waste time using a product that doesn't work or even worse, harms you. There is the risk of missing out on what you could have spent the money on instead.
Then there is the "100% Money Back Guarantee!" with "No questions asked!" This is great for the consumer but terrible for the business. As a consumer, I don't want to play twenty-questions with you trying to cancel your service or return your product. But as a business owner, don't you want the feedback for why someone wants his or her money back? Without that feedback, how are you going to improve your products or services? This is usually a false promise anyway because most companies will ask questions even if they said no questions asked.
The best guarantee I have seen was for a deodorant. The guarantee was that you would be so satisfied with that company's deodorant that if you weren't, they would buy you a stick of your deodorant. Now that's a risk-free guarantee.