It's different for everyone. Personally I think the concept is both pointless and insulting. I've been labelled a wide range on the scale (okay, well above 6) and many by people I don't even know so I couldn't care less.
However I'm going to be a bit romantic here and say that the last 1 point (10/10) is reserved for the one you fall in love with. Surely no one else is more deserving of a 10 in your eyes then. Just my two cents...