What Is High Maintenance?

I often hear people talk about being or knowing someone that is high maintenance.  But how do you define that?

Is it someone that is emotionally demanding?  Or someone that is financially expensive to maintain?  Or is it someone that generally has to have things their way?

When we were at Burning Man a woman was looking at an "art" display of women's breasts and commented that you don't see many "fake" boobs at BM because those women are too high maintenance.  I took a personal offense to that.  I don't see myself as high maintenance (although Tony may disagree). 

Without making judgement, I think of women that need regular spa manicures/pedicures or that spend a lot of money on cosmetic treatments as high maintenance.  But maybe that's how their men like them and therefore the men don't see that as an issue.  For that matter, is being high maintance an issue in a relationship?

What are your thoughts?  Have you ever had a relationship with someone who's "needs" were just too demanding or expensive?  If yes, what were the issues and how did you resolve them?  Can men be high maintenance?