Not only did I find the winning slogan ("I like Skyway Soap because it is as pure as the sky itself!"), I found that the book was packed with something I've chosen to call retroanachronisms: worldbuilding elements that were contemporary or futuristic at the time the book was written, but are distractingly outdated today. For example, in this futuristic world with bases on the Moon and Mars, Kip's small town has three paper newspapers, he has to "tune in" the local TV station on his hand-built black-and-white TV set (at one point the picture and sound go out and he tunes a station from another city "on the skip" but it's too staticky so he switches back), and the contest winner is announced on a variety show with singing, dancing cigarette packs. Not to mention the gender issues.
I have committed a few retroanachronisms myself. In "I Hold My Father's Paws," which must take place at least ten years in the future, I have a character remembering hiding something in a box of old CD-ROMs when he was a kid. Referring to something present-day as being in the past (in this case, a memory of something that was old at the time) is a great way of establishing that we're in the future, but it bit me here. There's no way the character -- who would be at most ten years old in 2011 -- would even know what a CD-ROM is, never mind have a box of them anywhere in the house. They became more thoroughly obsolete, and faster, than I anticipated when I was writing the story (2002). The exact same problem affected Back to the Future II, in which Marty lands in an alley containing bales of discarded 12" laserdiscs.
Retroanachronisms are, I think, impossible to avoid when writing fiction set in the future. You have to have some elements of the present day in your future world, for the sake of reader identification, and sure as shootin' some of them will turn jarring as the future takes twists you didn't anticipate. But they're fun to watch for in older SF.