Wait, old forum from 2008 with 12 members? That part blows my mind. Those tiny dead forums are like time capsules, and the fact that one link from there led you to a guy in Finland writing about card scrapers is wild. I read a 900 word post about sharpening something I don't even own like 3 times before, so I get it.

Wait, you actually bought it? From a rock pile ad?

Shoot a few test frames with your lens breathing just past the focus point and see what your wife says. Does she like the smear when it is a face, or only when it is trash and fences? My guess is she likes the ones where color turns into mud but you can still tell what the thing is. Try a streetlight at dusk and a brick wall up close, then ask her which ones look like paint and which ones just look broken. That will tell you if you are chasing blur or chasing her taste.