When I target a site, that's one of the things I look for... whether the ads suggest either multiple meanings in search terms or multiple audiences for the same term, either of which might make ranking for some queries especially difficult.
In one manufacturing area, eg, I ran across a large market in collectibles for the same item. To some extent, this double meaning influences searches themselves, as searchers try to refine initial searches to get ferret out the results they want.
Universal Search might cut both ways, making top spots for some channels easier to get, but reducing the number of top spots in others.
Something for Google to keep in mind. This is a fine point... but, by handing lazy searchers a smattering of specific top results, broken down by channels, Google might also be removing the motivation for these users, at least, to learn better searching techniques.