Reliability is a big issue in this industry. Who's reliable? Who's not? That works both ways, and if I had $1 for every time someone cancelled last minute, backed out, never replied, ect... Well, let's just say I'd be sitting on a beach somewhere.
When I go out of my way to accommodate someone's schedule, and they are aware I have done this, and then they back out... Heated is not the right word for the emotion I'm feeling.
My time is just as important as yours. I think it is a misconception that when a Provider is "blown off", it is what it is. Let me set that straight. I'm not sitting around waiting for an email to arrive so I can jump in the car, and come fulfill your fantasies. Although, it was I like to do, I have to plan and make arrangements for my real life to accommodate your fantasy.
I cannot imagine you'd be to thrilled if your client casually cancelled last minute, or just left you hanging entirely. Most likely you still get a cancellation fee.
Let's all keep this in mind for 2014.