We got Oreck's XL Pro Air Purifier in a while back, and it's been put through its paces in a big, open plan area, for which it's marketed. Pictured above is a close look at the collector grid after a month of use. For reference, you're looking at just a couple of inches of plate. Impressed?
Cleaning it off with warm water yielded the following soup: it got dust, by the looks of it, but not the kind of inky scum demonstrated at Oreck's website. Then again, we do have quite a clean home.
Our review is forthcoming.
Product Page [Oreck]