How often do you deal with return fraud?

I want to create a tool for owners to detect bad customers, but would like to validate the idea. I would greatly appreciate if you can answer some of these questions 🙂

How often does return fraud occur in your business? How much money / time do you think you have lost dealing with this type of stuff? What do you usually do when it occurs? Have you ever not shipped an item because the customer seemed suspicious? If you could identify a problem customer before shipping it, what would you do?

Thanks! If I get enough feedback / traction i’ll build something cool for ya’ll.