You must have a horror story or two that involves "clients from hell." This may be a no-brainer, but I was surprised to find a website dedicated to sharing those horror stories. (https://clientsfromhell.net/) It seems they even have a podcast about it.
On the flip side, if you haven't had any experience dealing with clients from hell in your service business, you are leaving money on the table.
“What?!,” you might ask. You heard it right the first time. You are losing money.