Actually, if something is so stupidly hard, it generally makes me more determined to not let it beat me xDD
I don't think there are any in OoT like that... maybe the water temple if you really couldn't find the last key... but in MM definitely. I've seen it myself- my dad just couldn't get past Snowhead dungeon, and he gave up on it. Heh, I picked up where he left off, but on my first time playing through MM, I used a (rather crappy) guidebook: there was no way I'd get through without getting stupidly stuck xD But I wouldn't say they're
too hard, no.
Although when I was younger, I had this happen in OoA, but I'm already past what I found hard xDD And the... 6th? dungeon in TLoZ, with all the flaming like-likes
C Also, the two rooms of darknuts before the recorder seemed impossible, but I found a stratergy eventually!