1. The pricing of anything you have to purchase, once inside. An airline gives you a lunch voucher for $10 when your flight is excessively delayed - and you're struggling to buy a snack with $10, let alone lunch.
2. Airport food that barely passes muster as edible food.
3. When things go wrong, and there's a serious delay - having to go back through security just to get a bite to eat. Then having to go through security again, because you went to the snack bar, and you're now almost certainly carrying liquid explosives.
4. There's never enough seats - particularly when thoughtless people have placed all their luggage on the seats - or they're lying down and stretched out over 3 seats and snoozing because their flight has been delayed for 6 hrs.
5. Finding a seat and then realising that someone has wet themselves on it.
6. Having a flight delay of one hour announced. Then after that hour, having another hour flight delay announced. Then after that hours wait, hearing about another 2 hour delay. It's called drip-feed, I believe.
7. Airport signage warning you about every infringement and penalty they can think up - but a lack of signage giving you directions on exactly where to go to find your gate, your luggage, or the way out.
8. People touting in airports - even though touting is banned (yes, I'm thinking of a number of European airports, here - and most Asian airports).
9. People smoking in airports, even though smoking is supposed to be totally banned (CAI promptly comes to mind).
10. Paying a fee for a shuttle bus between terminals, that should have been better positioned - or if this wasn't possible, then free transport provided.