Amy, I respect you enormously but I am most certainly not being smug or judgemental.
I have had great difficult accessing affordable dental care which lead to me losing a tooth. Having had another tooth knocked out previously, this left me two missing teeth, one on either side of my mouth, both gaps were noticeable. As the bone was not packed, I could not get an implant either, something that would I could never have afforded either. However, I saved up to see someone privately and got a bridge on either side. Yes, it was eye-waveringly expensive but it was some of the best money I have ever spent on myself. I sacrificed a lot to be able to pay for this work, something that was entirely my choice. Just last year I broke a tooth and it needed to be crowned. I refused to see any clients during the month it took for treatment to be completed because I was somewhat paranoid my breath might not be the freshest/the feel of the temporary tooth would be an issue.
So yes, I do understand that for many, they will not do anything about missing or crooked teeth for a myriad of reasons. But that's all by the by anyway, it's about poor dental hygiene; it is not excusable and a valid reason to decline service.
You're quite right about tonsil stones too. Thankfully, I have no tonsils either!