An 'undecorated' boot, of any style up to knee-high, is essentially an item of practical weatherproof/protective footwear, even if worn as a fashion choice, and therefore intrinsically 'male' in its origins and impact. But, if it has anything beyond a flattish or fairly low cuban/cowboy heel, it ceases to hide behind that facade.
A 'court' shoe (pump), although historically male wear, is in its modern-day iteration wholly female footwear, regardless of the height or style of heel.
It follows that a man wearing (long) boots, with or without modest heels and even if outside his trousers, is unlikely to register much on the CD/eccentric/fetish scales - but a man wearing even the plainest kitten-heeled pump in plain view will set the bells ringing and the tongues wagging. The saddest thing, however, is that almost any woman can wear any of those things with anonymity and impunity - as long as she doesn't fall over.