Having just read up on this again I will add one more theory to the mix. A recent theory suggested that it's not from ketones, it's from ammonia in the protein, and so it's more of an Atkins thing than an LCHF thing. Then, today, I read that the acetone in the breath ("pear drops smell") only occurs if the acetone is not metabolised by being converted to pyruvate before it escapes in your breath. So that suggests that raising your energy demand, aka exercise, might eliminate it. Want to try that?
What I do know is that it's not always or even often the case that people get 'pear breath' on low carb. Sometimes it happens but often it doesn't. I wish I knew why for sure.