Yep, if I want help from a stranger, I'll ask for it. (Unless I'm in some kind of dire trouble, but being a little clunky in LFR isn't exactly like lying on the street bleeding.)
If I'm healing with my safari hat on, and you whisper to me about it, and I don't know you, I'll just add you to my /ignore list.
If you're a friend, that's different. Why don't I treat strangers like friends? Well, because they're not.