My theory is that publishers in the Forties and Fifties sold ads for their whole line, and appropriate placement in "relevant" titles was not a priority. For example, there are 10 pages of ads in a 1950 issue of "Romantic Confessions." These include full page ads for “Motor’s Auto Repair Manual" and a “Life-Like Rubber Skull and Luminous Ghost Mask!" and a small ad for the book “How to Get Along With Girls.” Assuming romance comics were mostly read by women, these ads don't seem "targeted" properly (not to be sexist about it). However, I agree that "The Pleasure Primer" seems inappropriate for ANY comic. Stravon also advertised in pulps and other magazines as well as comics, so perhaps this was just a slip.
Link to the book:
Black Swan Comics 1