The young girls are warned about sporting men, who look handsome and speak well -- but have a deck of cards and a bottle hidden. "Beware, young ladies, they're fooling you; Trust them not, they're fooling you; Beware, young ladies... Beware, oh take care"
Credited in the Digital Tradition to Blind Alfred Blake (which Paul Stamler points out should be "Blind Alfred Reed"), but -- since the piece has been in circulation since at least the 1880s -- it would appear that Reed, at most, retouched it into the "popular" form.
Laura Ingalls Wilder quotes a scrap of the song in _By the Shores of Silver Lake_ (chapter 6). If legitimate, that would push the date back even farther -- to 1879. - RBW