Not enough photographers over expose- sounds a bit naughty.
I tend to over expose by a 1/3 stop in most images. I think it makes an image look brighter and adds a lift when I post edit. This is especially true as I add more black to an image. The contrast of the slightly over exposed whites and the boosting of the blacks adds density to the images I like.
For portraits, this works as well by brightening faces which is a very appealing look. Look at the previous blog post of a Headshot to see what a 1/3 stop over exposure looks like.
In this scene, I want the whites of the walls to be much brighter so as to contrast the dark shadows of a high midday sun.
And if you look carefully, you can see me:)