Because in our case, it could mean that the female is attractive and has good physique esp. stature or it's implied that she has good sexual appetite/stamina and that's why it's best to avoid all these terms altogether and stick to plain and simple pickup lines :)

EG "a right mardy mare"

Probably NSFW for language http://www.townx.org/blog/elliot/insulting-british-colloquia...

http://www.urbandictionary.com/define.php?term=mardy

I don't think "mare" is that insulting either, an insult-lite at best.

Used in relation usually to being stubborn.

"come on, do your homework, you're stubborn like mare / you stubborn little mare"