Well, I think I can go dig up the pop charts from the 20s and prove you wrong, but I'll let you have you way in thinking that nearly 100 years ago, maybe things were different.
There were many foolish songs in the twenties, but they were not vulgar by today's standards and they were known by young and old.
example:
Marsydoats and doeseatoats
and little lambs eat ivy
a kidle eat ivy too
wouldn't you?