What is a work-appropriate shoe?

It's really humid here these days, and especially hot and humid in my closet where I get dressed - hence the sleeveless top.  But I figure since the quarter hasn't started yet, I can get away with it.  (Lots of other people around here wear sleeveless tops.)

But I'm super excited about finally wearing my first pair of Christian Louboutins to work!  These are not really work shoes I think - given how much my toes show in front ("toe cleavage").  But that's becoming more common these days, and again - summer - so I figure now is the time to give it a try.  What do you think?  I've always considered open toe shoes (even a tiny peep toe) to be inappropriate for work, but I always see them featured in fashion magazine spreads of what to wear to work.  I've sometimes read that tall heels are inappropriate, but I've never followed that.  I think super tall heels with platforms are inappropriate, but a 4" heel is okay to me.  And now there's this new question of "toe cleavage."  I have no opinion yet.  During the summer, several people around here wear very open sandals, and one woman even wears flip-flops, so I don't think anyone will notice my shoes for being inappropriate.  I am curious if anyone will notice my shoes period.  I'll let you know.

(Top: Target, Pants: White house black market, Shoes: Christian Louboutin, vintage, via Lollipuff.com)