Yeah I have always found it annoying, if you're going to bother liking it, just write a comment saying :sorry to hear that" etc.
What irks me more is vaguebooking. I had a friend say last week "I don't like to be vague on FB but (insert vague sentence here)" She got some comments, then followed it up with a comment saying she didn't want to talk about it on a public forum. Why mention it then!?! So attention seeking IMO.
I am truly sick of FB, I just wish that so many people wouldn't rely on it to communicate with me all the time.