That was one of the most striking differences I noticed when I saw a bunch of photos from c. 1970 of my hometown (Toronto). Everything that wasn't freshly painted was grubby in a way you don't see anymore here.
For some reason aesthetically I prefer the coal-covered limestone buildings. They are just pleasing to look at. So in a way I find it strangely disappointing that they get pressure washed.
1971: https://www.blogto.com/upload/2014/03/20111020-royal-alex-f0...
2009: https://upload.wikimedia.org/wikipedia/commons/7/71/Royal_Al...
We phased out most coal in the 70s with the last eliminated in the early 2000s. I do not miss the vibrant orange sunsets in summer.