I turn away paying(automotive) customers all the time Paul. It’s not always about the money. There are certain people/customers where enough just isn’t good enough and the job isn’t worth the hassle that’s inevitably going to follow it. I don’t like assholes or knowitalls because those are the two types that will find something wrong with the work and nitpick/lowball you afterwards. Nip it in the butt first time around and you don’t deal with it.
Me, Synapse, CRC, etc all play that game. Any private shop owner is going to weight the numbers and make these kind of calls. Occasionally you’ll get that job that may not pay well but the notoriety of it is worth the time, but those are FAR and few between…