These spots would be susceptible to graffiti, which in itself would draw attention to the product and result in fantastic mind share. Then again, maybe we should have an advertisement shoved in our face every time we turn around. Over the years publishers have realized that selling every square inch of a page for ad placement turns off readers. To get away with thick, ad-riddled magazines such as Vogue requires finesse. But even the fat magazines don't sell space on their covers or on the spine, as the Comdex catalog does, for example.
Some trade publications sell any white space they can find.
They take on a cheap quality. Another type of dubious advertising is popping up in newsgroups, to the annoyance of the members. While this type of spam advertising is recognized as such, a new version has emerged that is just as tawdry. This kind also has bogus postings, only they're found on various classified ad sites. It's a particular plague on the free classified sites and will kill them off.