Impossible. I don’t believe because this is too unprofessional. I have ex-colleagues who became customers/suppliers. We treat each other professionally at work even though we drink together, doesn’t matter if it is post 35, 45 or 55 years old. I CANNOT ask a customer even if he is my close friend to close eye. Neither will my friends who happen to be my suppliers do that to me. As a professional, we have to account to our management, customers, society at large and whatever interested parties defined in our ISO9001 quality manual. There is no such thing as ownself check ownself because I will either get a big fat nonconformance for rectification or the police will be involved, true for a staff as it is for the top management. My projects are all auditable by quality, finance etc. Even going to lunch with suppliers/customers, accepting gifts even on private context, business trips are mandated by global corporate compliance with strict guidelines like not more than USD$1 or not allowed. You violate that guideline, you either get dismissed or you face the law.