...And they are treasured.

Some clients don't and maybe they are able to book an appointment when they ask again, maybe they are not depending on the circumstances of the previous cancellation.

Inappropriate cancellations are accepted by me as a part of the game but don't go without noticing or consideration when my time is requested in the future.

If you have something to do, are double-booking because you feel entitled to doing that, just don't feel like after planning in advance that it that is fine.  
But reasonable notice and/or generosity goes a long way.  I'm especially generous with my time/service and or discounts in the event I have to cancel and I try very hard to honor all of my obligations once I've said yes these days.

Most of my guys take very good care of me when they have to cancel if its so last minute that I cannot salvage my day...

And I feel like my circle of friends has naturally purged and sorted itself right when someone proves themselves to not have a basic sense of respect about our arrangements with a shady cancellation.

So I don't have any real complaints about this issue- when it comes to cancellations its all good.  Observe basic decency and we are good.