In regards to buyers who do not pay, we do not have a large recurring problem with buyers who choose to do that, but it happens on rare occasions.
This happens in all marketplaces.
We try our best to prevent it, and investigate each instance and take farther action if needed.
For full transparency, we also remove the item from our sales archive and update it's dedicated page to let people know it didn't go through, for the purpose of not claiming false numbers. We feel this is in the best interest of the community.
Regards,
Jarred