I have found loads of benefit by removing the "surprise element" out of people in society. Meaning, there will always be flakes, jerks, assholes, etc. That will never change. The only way to protect oneself against them is to not be "surprised" by their actions and actually plan for them. For me, it removes my emotional reaction to their action and I stay smiling. : )
PS. Cancellations are part of business and part of life. But no shows are disrespectful. Up the quote you gave them if they return to include what would have been the deposit.
Kudos on not feeling you must always be dressed up and ready to be put on public display. I love a girl who is unafraid of being herself -whether dressed up for a prom or playing mud football. There is nothing sexier!! As to appointments though, I'd never cancel on you! What kind of idiot was this that didn't show up? I will admit freely to not being consistently on time, but not showing up is an entirely different problem. It shows absolutely no respect for your own word. To me punctuality is comparatively entirely explicable. It is so easy to be late, for reasons few people can ever totally predict. Not showing up at all though, now that is ridiculous and only displays contempt for doing what you have agreed to.