Sometimes the most plausible people are those who just don't turn up. I've had brides, bridesmaids etc do a disappearing act, too.
I had one bridesmaid who was in desperate need of help. The wedding was only two weeks away, she was maid of honour, and she was pregnant (but hadn't been, when they bought the dress). She was about 6 months along, and getting bigger by the day, and her dress could not be fastened, at all. She begged me to squeeze her in (in all ways) so I found room in my diary that day.
Guess who never showed up? I even texted her to check she was okay, as it was only three hours since I'd spoken to...she ignored me.
She was called all kind of rude and totally unprintable names by me, as I'd had to ask another client to move her appointment around, purely so I could fit this woman in when it suited HER (she had kids she needed to pick up from school).
I no longer bend over backwards for anyone, and I certainly would never ask another client to change their booking again.