I have a friend who actively avoids spoilers for films, he was the only one at the midnight screening of Episode I who saw the double bladed Light Saber for the first time. so there is definite merit, though it is getting harder and harder.

I avoided a lot of the AOE trailers and watching them now I'm glad I did as I would have seen SPOILERS >> the block scatter transformation which I really didn't like. <<

It's doable, especially now there is more of a social awareness of not spoiling for others (this board tends to do a pretty good job of labelling spoiler content), but it's still very hard due to the amount of material out there. if you're not careful you'll see a spoileriffic tv spot turn up and play before you even have a chance to look away.