After that last one, I started spreading the word about what really happens. A co-worker thought he was being really smart when he went with the workers to the Home Depot to make sure he'd actually get his materials even if the workers didn't perform the work. However, the coworker didn't have a truck. After loading the materials into the workers' truck, he went home. The workers returned the material, and the co-worker was out the money.
I've had good luck going forward never paying up front. I'll make progress payments as the work is satisfactorily completed, and I may pay more if I need to get someone else to finish a project, but I've never had to take another total loss again