I've recently been compiling a list of stinging critiques which have placed a stone in my shoe when enjoying a particular piece of life or pop culture.
For example, I remember my Dad telling me that 'Batman' was the story of a multimillionaire, Bruce Wayne, who went around beating up people less fortunate than himself. He was of course right and it took me years to get back into the caped crusader. As with all great stinging critiques this was delievered very casually and without malice. I think we were walking in the countryside at the time as I can clearly remember looking at my crestfallen face in a puddle and realising he'd hit the nail firmly on the head.
Another example of a stinging critique is the observation that in films/tv dramas no one ever says goodbye on the phone. They just hang up. This was pointed out to me back in the mid 90's by a friend and still to this day it irks me. What's so wrong with adding 'bye' to the script?
There's a bit of sci-fi scriptwriter's shorthand which is particularly well known to hardcore Doctor Who fans, "reverse the polarity of the neutron flow". It's a meme from the era of fanzines and geek conventions that predates the internet. I remember a friend of mine explaining it and telling me writers use it when they're in a bit of a bind and need some technobabble to get the hero out of an impossible situation. "And now, if we reverse the polarity of the neutron flow there might just be a way out of this..." and hey presto all the Daleks/Klingons vanish in apuff of smoke. Having this pointed out to me lifted the veil a little with quite a few of my favourite sci-fi stories as I realised a lot of them didn't actually make any sense. They just sort of ended with some flashes and soaring music.
There are many more examples. Don't even get me started on Santa and the fact he gives the best presents to the kids whose parents are richest.