The red car example, though, suggests a modification of an adaptive filtering.

That's exactly what I'm getting at. In the case of car color it's unlikely that everybody, overnight, has decided to buy a red car. In the case of words, it may well be that a given word is enjoying a flash of popularity. OTOH, if I were searching for a given word and finally, after much effort I found it, then having it show up everywhere, that might be more like the red car example.