I was travelling on a night train from Edinburgh to London, it was unusually quiet even for midweek and the sole occupants of my own carriage at the far end of the train consisted of an elderly couple who were fast asleep and a student facing me from the table on the opposite side. We passed comment occasionally but we were both rather more focused on our own books than conversation, I even slept myself for a few hours waking up around 3am.
There were still a few hours until the train arrived so I grabbed my bag from the overhead rack, nodded at my companion and wandered down the carriage to freshen up and get changed. On arrival there was no chance I was stepping inside that restroom given the state it had been left in by previous occupants. I quickly brushed my teeth in the alcove outside, but getting changed was out of the question since the few people in the next carriage were clearly quite active.