Well, it's been like this for a long time and I have witnessed this many times in my mom's business which I later had to manage for some time. Funny enough, people like you described aren't outsiders or new customers, they're either long time customers, families, friends, and acquaintances. A stranger won't come to you for credit atall, or get it and not pay. The solution is simple. If you sell on credit and they didn't keep to their end of the agreement, they have to face the consequences even with embarrassment. Better not to also sell on credit atall no matter who.