timfountain

Indeed, dirty bathrooms and also smelly bathrooms, mainly due to inadequate ventilation. There's nothing like getting off a redeye and enduring the disgusting stench of 100's of other people's 'early morning movements' all mingled together.
Water-less urinals.... They just don't work and I don't want to smell other peoples piss.
Since I am on a restroom tirade. Small stalls. Look, I am travelling, I have multiple bags with me. I hate squeezing into a stall and rubbing against the dumper, walls or door to fit myself into an inadequate space.
Also people people who never learned to read. 'Stand on the right, walk on the left.' It's not that freaking hard....
Signage can often be an issue. Either inadequate or confusing.
I also find most airports to be too darn hot. Especially in Asia and Europe.
Brand new car rental facilities that feel like they are in another state, and shuttle busses grinding backwards and forwards between the terminal and the facility. Why not have a proper train link? Specifically DEN and BWI come to mind.
Finally lounges can sometimes be very hard to find. It sometimes feels like the airport management don't want to help you find them...