The friendly button causes me the most anxiety because I always worry that it's just the...pity button, or something. And I feel like if someone marks my post friendly, there was no content of value in it but people are just going, "Aw, sucks to be you, here is a sympathy point." I recognize that this is completely paranoid. And when I mark posts friendly, I am sometimes being totally literal, as in "This person is so kind and friendly!" and sometimes I use it for the equivalent of "hug" but it bothers me slightly that I can't differentiate the two. But then I think if I could, I might be more paranoid because then I couldn't hope people were being literal--I'd know it was the sympathy point. But maybe not if it's called "hug." I like hugs.
I have trouble interpreting the buttons, too. I don't see the friendly button as a pity thing. For me it's usually for when I want to say that person has been friendly or offered something personal and thus tried to be a friend. So it's literal for me, like for you.
I also use it to show support (as distinguished from pity) but only because there is no separate button for that purpose... If I give you a "friendly" in the future, I promise it will never mean, "sucks to be you..."