I do feel like Frankfurt (Main) Hbf used to be WAY nicer before CoViD-19. I went there in 2019 for the Frankfurt Autoshow and the station and its surroundings were pretty nice, even at night.
In 2023 and 2024... not so much. I wasn't bothered at all by anyone, but the station's McDonald's was filled to the brim with people, as it was the only place warm and open late into the night.
In 2023 I had to change trains at Hannover between 2AM and 4AM. Up until then it was the place where I've saw the most homeless people crammed inside a railway station.
Again, both the lounge and the waiting room were closed, so only the station's MacDonald's was the only place were someone could have a place to rest, warm up and charge the phone.
When that facility closed, I took the time to walk around the vicinity, through Georgstraße and Kurt-Schumacher-Straße. There was no living soul in sight, which was both reassuring and frightening at the same time!
People don't recommend passengers to change between Paris Gare du Nord and Gare de l'Est by foot. Gare du Nord is infamous for pickpocketing, and I came to talk with a Brit that had his wallet stolen right after leaving that station.
I was also pursued at least twice when changing metro lines at Gare du Nord. One of my friends got pickpocketed, but fortunately he had nothing of value where they went.
A lot of metro stations reek of urine, and it's common to see police agents escort people out of the platforms and hallways.
At Porto São Bento there used to be a lot of begging at the station's entrance. And robbery/pickpocketing is rampant. One of my aunts got her bag stolen while sitting at the station's coffee shop.
Drug dealing happens in plain sight in the vicinity. If you walk through Rua das Flores at least one man will approach you to sell you Cocaine.
Lisbon Oriente also has a long running issue with beggars and homeless people. The problem got way worse with the housing crisis. People are often bothered when eating.
Every time I go there and eat at the terrace I get approached by a beggar, sometimes twice by different people. I ended up starting eating inside because, at least up until now, they don't bother people inside.
Towards the bus terminal the underground passageway also reeks of urine.
Finally, the vast majority of stations in Portugal are just god awful. More often than not there is absolutely no staff week round. The smell of urine is found in every nook and cranny. Every weekend there also vomit in the floor. Platforms are filled with cigarette butts. Graffiti is an absolute given. Stations south of the Tagus have their equipment stolen for scrap.