My guess on why that vacuum cleaner ad was in a comic book is that they must have been trying to advertise to the college kid that was on his own or the post-college guy that got his first apartment. The thought process must been the kid on his own for the first time might have needed a vacuum cleaner in order to make his place somewhat respectably clean. There probably wasn't a great effort to put these vacuum ads in comic books but it was just done every so often just to see what could happen. They might have also thought that the mom cleaning the young kid's room might have discovered the comic books and looked at the ads. Imagine cleaning your kid's room and finding a comic book with a vacuum ad. You might have gone, "hmm, maybe I need a new vacuum?" It's a bit of a stretch but that's just my guess on the matter.