One thing comes to mind is to review childrens' song books and see how many contain versions of traditional songs.

A specific example comes to mind when I was singing 'The Shearing's Not for You' (per Stephen Sedley's Seeds of Love) and my mother was disgusted as in her Glaswegian school she had learned it as 'Will ye gang to Kelvin Grove my Bonnie laddio' and firmly believed that folkies were just making up rude words to nice songs.