How to hire a product manager

Having come back to the UK from US (where Product Management is much more mature discipline), I have been saddened (and, on occasions, appalled) by the level of ignorance of non-Product Managers about Product Management.

Having seen some pretty 'shonky' job advertisements for Product Managers, I thought I'd better lay out some guidelines for everyone's benefit: How to hire a Product Manager.

Comments welcome!