So if you know nothing about it, why did you feel the need to comment on it at all?

Do you tell cancer sufferers "Wow, I can't imagine what it must be like to know that you're going to die soon. I know nothing about your illness, I'm just so glad I'm fit and healthy!"? If so, do you think they're grateful to you for rubbing it in?

(Don't bother answering -- I dread to think how tactless you could be if you were really trying.)