If you were anywhere near a radio in 1967, these lyrics were seared into your brain …

“If you’re going to San Francisco / Be sure to wear some flowers in your hair.”

The singer was Scott McKenzie. It was the summer of peace and love.

Almost 50 years later, San Francisco is in a dry summer of … piss and loitering.

“San Francisco is an affluent and vibrant city. It shouldn’t smell like stale piss,” Debra Saunders declared in The San Francisco Chronicle.

She’s a nationally syndicated columnist, but does not opine from an ivory tower. Ms. Saunders has a nose for news: “The smell is worse than I have known since I started working for The Chronicle in 1992. It hits your nose on the BART escalator before you reach Market Street. That sour smell can bake for blocks where street people sleep wrapped in dirty blankets.”

In the finest hometown columnist tradition, Ms. Saunders talked to the mayor and rode around Nancy Pelosi’s congressional district with the police.

They found lots of drug-addled homeless people, some of them batsh** crazy. This is what happens when a city run by liberals spends decades putting out a welcome mat.

But that tide may be turning. Laws are being enforced; neighborhood associations are paying privately for sweeps. That drew pushback from across the Bay, where the Cal-Berkeley Law School Clinic put out a report titled “Punishing the Poorest: How the Criminalization of Homelessness Perpetuates Poverty in San Francisco.”

The gist is that laws against things like camping on public sidewalks are the equivalent of Jim Crow 2015.

Nobody is arguing that cities shouldn’t provide more shelters and mental health services for the homeless. But this report should have come in a golden yellow cover. Piss scented, of course.