I've been thinking about it a bit more, and you're all welcome to tell me I'm inconsistent and thoroughly illogical. Part of it is certainly the perception of product placement, but there's something about the visual breakup if you will that accompanies many of these categories. A category about the Smithsonian Institution is one thing; a category in conjuction with Smithsonian magazine with their logo above it would be murh more likely to make me roll my eyes. By the same token I also find something mildly jarring about the categories that have one celebrity doing videos for all five clues and have them announcing the category (or even when it's a member of the Clue Crew). Those seem to break up the flow of reading the category names, too.
Like I said, it's illogical, but for whatever reason I don't care for it.