Enjoyed the thread, I also went to Salford Uni in the late 60's and lived locally. Regarding the soap suds, I used to cross the footbridge below the weir off the Crescent and the pollution used to give rise to a mountain of suds which used to take to the air along the river and you had to dodge between the huge globs. Croft as a few people have said, was a wasteland for playing by day and coortin at neet. Undercroft was a common name for the huge cellar area below railway stations used for goods and storage especially Piccadilly and StPancras.
Incidentally, no-one has pointed out that Salford was the first city in England to go smokeless and ban open coal fires. Manchester Exchange was in Salford and shared England's longest railway platform with Victoria, the only intercity station platform. Salford was a City then in its own right with a cathedral that nobody knew about. (go back far enough and Manchester was part of Salford)
I was on the folk club committee at the Uni, we used to get up to 300 people there, mainly locals from the tower blocks, but never had McColl in my day.
I remember an evil sulphury smog in 1968 there but never saw another that yellow. The towpath along the Rochdale Canal was a great way to see the city from a different angle.
Wassail
Bill