I particularly hate wet days on the London Underground (well I particularly hate wet days anyway). You have to find places for your sodden umbrellas, or you usually get dripped on by someone else's sodden umbrella. There's also that horrible musty smell of hundreds of wet coats and jackets slowly drying in the human heat. Or the vile smell of wet moquette from the Tube seats. Then that horrible realisation when you plonk yourself on a seat which has been vacated by someone who "didn't have an umbrella", like I did yesterday. Yuck!
Makes note to self to always feel seat before sitting on it. Then again, on a late night train you're taking a bit of a risk as to what the "wetness" might be. I'll leave you to make your own conclusions!