There is a grubby side to the city, no doubt. I think those who go from their apartment to work, or from their hotel into El Centro in a taxi, will never see the best this city has to offer.
You need to brave the dirty streets and dog crap, and walk. The parks and plazas that can jump out at you from any street corner offer a beauty that will surprise and enchant you. Buildings that date from a golden age cannot be viewed fram a taxi window their beauty starts above first floor level. Cupolas, towers, vaulted cielings, colonial master pieces, can be found everywhere, but they will not find you, you must go out and seek, make the effort and Buenos Aires will reward you a thousand fold.
Those of us who love the city are not blind to it's faults, but it's beauty make up for it all.
On the sidewalk issue, they do belong to the owners, but they are not responsible for the damage. My own sidewalk was dug up by the telephone people, almost before the building was complete. Nice shiny tiles were replaced with poor and very thin concrete. So if you fall outside my building don't blame me (or my builder).