So I lived in SF for six years, and it was absolutely the dog piss that did it.

I know this because outside my apartment were two metal utility poles. One, right it outside the door, was the dog piss spot. The other, 20 feet away, was not.

Guess which one corroded and had to be replaced after three years? It was the one that absolutely reeked of dog piss right outside the door.

This is not only real, it's not the first time it happens. It's a well known problem that occurs all over the world wherever humans erect steel post and also have dogs at pets.

Apparently people peeing on steel objects is an actual serious structural issue.

Here's a bridge in Sumatra that got hit:

https://www.loosewireblog.com/2004/11/urine_corrosion.html

the 1,177-meter long and 22-meter wide bridge

Last Friday, The Jakarta Post carried a story headlined “Bridge in Palembang may collapse due to excessive urination”. Not really much more needs to be said, but let’s spell it out. The bridge is sloping. This ‘irregular slant’ had been confirmed by Professor Annas Ali, a highway and bridge expert at the public works office who conducted research on the bridge recently (presumably by standing on it and noticing that he was not standing, as we engineers call it, ‘straight’).

Upon further inspection officials noted that, in the words of the Post, “one of the reasons for the apparent structural deterioration was due to the frequency of people urinating on one of the steel pillars of the bridge, causing it weaken due to the corrosive forces of human urine.” This deterioration can be measured since you can actually feel the bridge ‘resonating’. This was proven by the head of the city’s transportation office, Syaidina Ali, who advised the Post reporter to ”try standing on the Ampera bridge. If the traffic passing on the bridge is heavy, you can feel it moving quite a bit.”

I see another reference to civil engineering proceedings on a bridge in the Carribbean that faced a similar problem.

Also what “salt water mist?” The Castro is inland, and it’s not like there are huge waves blasting clouds of mist into the air.

You're just mad because they won't let you piss on things anymore.

Dog piss is a salty slightly acid stream of water. I.e. it is more direct damage than general mist.