You may remember my "Cindy the Salesgirl" posts from back in June. The story below, "Betty's Boutique" is almost exactly the same as the "Cindy the Salesgirl" stories conceptually. In both, a young, fashionable woman is asked to model the newest in clothing styles for her clients -- only to get a surprise explanation when they don't purchase anything.
From what I can tell, "Betty's Boutique" appeared in three separate issues of Girls' Romances. This particular one, drawn by John Rosenberger, comes from issue #142 (July 1969). The Betty stories were all put out after the Cindy stories, so it is obvious which set the standard. Though they are basically the same stories, Betty seems a bit older, and she is the owner of the shop, whereas Cindy seemed to be an employee of a shop.
I personally am a huge fan of the O. Henry style ending. Having worked in retail though, the reasons for people in real life trying on a bazillion items and not purchasing anything are far less interesting than in these stories, for sure!