I would bet it was cleaner then. The shit they're finding now is most likely a direct result of fat slobs using pools as their own personal bath for all of the places they can't reach on their own "body" to clean. Shit stuck between their ass cheeks, fungus and mold between their folds, rotten food that they tucked away under a slab of flab to sneak out of a buffet and forgot about. Seeing fat people in the 70s was rare, there were a few more in the 80s, but still nothing compared to today.