This is called prevention.
There is a population of approximatively 2.9 millions of rats in Paris. (Pierre Falgayrac)
For a comparison, New york counts from 10 to 30 millions rats and London even more. (Bob Sullivan)
Those numbers are logical, big cities, big sewer network etc. etc.
Fast food and growing incivilities make the number grow a bit, that's why authorities are reacting, cause you can see rats on the Quais de Seine pretty usually now, which is normal, it's near beans and water...
But i understand people don't want to see them.
Anyway, Paris doesn't look like what you're describing at all.
I don't know about the smell, maybe parisian girls perfumes too well for me to think about it, but I never had much issues about it... It's a big city with car traffic, just like any big cities.
Authorities tryna make it better, Quais de Seine are now forbidden to any cars.
There's that green ticket rating CO² car are rejecting, When you're not up average, you can't even enter Paris without being sued.
Parisians can also sub to an electric car network, just like the vélib.
Ngl, Parisians aren't the best at throwing stuff in the beans, but calling Paris dirty is such bs.
Nowhere near big cities in South America or in Middle east, or India.
I live there, i think you'll agree i should be the more concerned about my living conditions...
That "been there this summer" is gold tho.