Good customers - Bad customers
Good business is having the awareness that all customers are not the same.
You get good customers; and you get bad customers.
Bad business is spending way too much time and money worrying about bad customers.
An over supply of bad customers will guarantee that your business fails.
Good business is having the awareness that all customers are not the same, being able to tell the difference between them and knowing how to handle each individually.
If you only ever worked with the very best customers; you would spend the least amount of money delighting them with the value that you offer, they would sing your praises obviously only to other good customers, they would be unreasonably loyal over the years and, without hesitation, buy high-margin items from you repeatedly.
Idyllic right?
Yes, and completely possible if that is what you want.
Bad customers you literally want to actively discourage from talking to you. They're not fit for purpose if your strategy is to only welcome the custom of good customers.
Who your serve is a choice; there is a lot of power in making it a conscious one.