My friend said to me you don't see people when everything go alright. You tell a lot more about people when things went wrong or you have no "use" to him / her anymore.
Recently, I got a couple of invoice I couldn't get the money back because I thought "friend" will not cheat you and it was all ok for a long time.
1) customer closed the business
2) customer changed to another supplier (and so, he / she doesn't need your things anymore, it means you have no use)