I run my own consulting firm and I offer a money-back guarantee.

I had one very short-term client who was dissatisfied with our service in spite of very clear deliverables. Nonetheless, I didn't hesitate for one second to give them back their money.

In simply offering to give them their money back, they refused the check and completely shifted their mentality towards us. They became advocates for us and then said they appreciated our work.

I've never had to give money back with a money-back guarantee and it has only strengthened our brand.