For me, I think it is a matter of my more conservative fashion tastes. I tend to lean towards smaller heel heights, solid colors, simple cuts and lines for the office while steering clear of what is trendy. I think we could all agree that there is clothing that is unsuitable for work such as a cocktail dress, jeans with more holes than actual fabric, workout gear, just to name identify a few of the far too many examples of such. Likewise, I think that, when it comes to heels, there is a height where the line between professional and "to be used elsewhere" is reached, but where that may be is certainly subject for debate. For me, personally speaking, that is ~3" to 3.5" exposed, ~4" covered by pants, total height even if there should be a platform involved. I also think one has to look at the color/style/print/material of the shoe to determine if it is office worthy. I love animal print heels, for example, but to keep them appropriate for an office environment, 3" max height is my limit. Any height above that starts to push them into "club wear." This, in turn, give rise to the question of "Classy or trashy?" I do not know if there is a bright and agreeable line that separates the two but there is one that does exist.