Sometimes people ask me what "overtness" is. Well, here is a good example of overtness from Cat Power, courtesy of billboard.com:
"Singer/songwriter Chan Marshall, better known as Cat Power, is the subject of the upcoming documentary 'Speaking for Trees: A Film by Mark Borthwick.' Due Oct. 26 as a CD/DVD package via Matador, the project is largely made up of a two-hour Cat Power solo performance in the middle of a forest, capturing all the ambient sounds of the outdoor setting."
When we speak of someone being overt, it means they are desperately (and obviously) trying to show how weird or interesting they are. Advanced people don't need to make overt gestures like playing in a forest. They might do it, but they don't need to do it, if you get the distinction.