Business with a bad partner, how many times?

Ofc. A rotten tomato can spoil good quality tomatoes too. I would say it depends on person that how much he badly want to spoil your business.

It's very bad, of course. No matter where we go or what we do, we seems to meet the Fraudsters, the bad payers, or the bad suppliers. If we're lucky, we can avoid it. If we can't avoid them, we'd better keep a proper distance so that the relationship doesn't get too complicated. That's what I think.