How many dealers advertise stock they don't have?

[So]

I've been looking for a particular Parmigiani Fleurier watch over the past couple of weeks.

It's advertised on the Parmigiani website - Parmigiani in Mayfair say it's discontinued.

Chisholm Hunter has it advertised on their website - an enquiry revealed that in fact they had never had one and only one was made for the UK.

An American dealer is offering one in its sale - No response to email and their T&Cs declare that they don't always have the stock they advertise.

So, how common is it that dealers advertise stock they don't have (and cannot get)?