I certainly did not take all of the lines and did not alight at all stations I crossed, but I was still prepared for much worse! To provide a point of comparison - the busiest stations in Ottawa all smell of urine almost all the time and they see much less traffic than their counterparts in Paris. It is in some ways a uniquely Ottawa problem but it was still nice to use the Paris metro to travel in the city.

Vienna metro was even cleaner and slightly less sketchy than Paris, but that is also not a fair comparison in terms of size and demographics. The Delhi metro is almost equally impressive as Paris's in convenience but feels about as clean as Ottawa.

For anyone interested to learn about the nighly cleaning routine for the Delhi metro, I strongly recommend to Google something like this: Why is the Delhi Metro clean?

Most Indians gush at the cleanliness of the Delhi metro. It is a world ahead of most average India Rail cars and stations. (I'm not speaking of long distance, upper class cars. Those are amazing, but ridiculously expensive.)

I spent almost 7 years in Paris, now 6 months in Tokyo. The metro in Paris can't even be compared in terms of cleanliness.

The old Marunouchi and Mita trains used to be pretty dirty (by Tokyo standards!), but both have been upgraded in the last five years. The classic "oyaji smell" is gone from both trains now.