Charing Cross in Glasgow. It's not the clientele (there are ticket barriers) - it's the station itself.
Charing Cross is in a deep trench, below street level. About 30% of the station is open-air, and it's quite light and pleasant. But the other 70% is in a tunnel below a 60s concrete building. It has narrow platforms, bright yellow walls, and really dim mercury lighting.
Getting from the street level to the platforms of Charing Cross involves a lot of stairs. But the stairwells aren't straight. Each stairwell has 3 or 4 90 degree turns - a different direction each time. It's really easy to run into somebody if you're going up or down the stairs in a hurry.
There's also a problem with the sewers in the tunnel just to the west of the station. Travelling through Charing Cross is like a stench-lottery. On a good day, the aroma of Charing Cross has vague undertones of sewage. On a bad day, the smell is horrific.