I created a mintpal account to vote but didn't realise that you have to trade first xd.
So when/why are we being added, is it because of the recent growth of because we are high in the voting list?
I would say Yes.

Exchanges will add when they see other exchanges getting volume and want their cut of the action. simple economics.
I've been active in Polo trollbox, the scrolling sucks ass though.
Are there any recent examples where mintpal has added a coin that hasn't been voted for? Just wondering if they still do it.