It seems they are rather restrictive with their results. I tried it with "what is cuil?" and didn't get a single answer.

Also I don't really expect to get that much improvement from the typical one-shot-editbox searchengines anymore. There's only so much information you can get out of a handful of words (that is unless they start to actually understand the intend of questions and content of pages).

I suppose results could improve if the searchengines would enter a session or dialog after the first try. Some way to make clear that you're still searching the same stuff, only trying other words because the first result haven't been good enough. I think when I fire off several searches in a row far more than half the time the reason is that I'm trying to improve my results. Cuil's categories are a step in that direction.