Are guys really that oblivious?

A few months ago I got a haircut. It was a pretty drastic cut from what I had before, and I liked it. I went to a YSA dance (yeah the same one that had crappy music; I have alot of blog ideas for this one night) and wondered to myself who all would notice. I figured that most of my girlfriends would say something, but would any of the guys say anything? I kind of assumed none of the guys would notice; although, I did have one guy comment on my new "do."

This makes me wonder, why is it that guys don't seem to notice things like haircuts? I mean obviously it's not true for all of them because I did have one notice, which then makes me think, perhaps they do notice, but they don't want to say anything. They don't want to seem "womanly." So which is it? Are guys really that oblivious, or is it they don't want to seem like a girl?

It seems as if it is one of those eternal truths/well-known facts that guys are just not as observant as gals, but with every rule comes an exception. I think that most guys do in fact notice things like haircuts, new clothing, etc., but not all of them say something about it. Perhaps they don't think that it's that important to say something about it. Maybe they actually don't like this new thing, so to avoid getting asked, "What do you think?" or "Do you like it?" they just pretend they don't even notice something's different. Then there's what I thought earlier, because girls do tend to notice things more than guys, men fake obliviousness to remain manly.

I'm not sure I'll ever answer this question because I'm sure you all can tell me examples of when a guy really didn't notice something, or when he did notice and comment. But, feel free to tell me these examples anyway. Let's try to get somewhere with this "chicken or the egg" type question: Are guys really that oblivious?