I checked the dish on my trusty Park TS-2 truing stand.

I thought it was so crazy that I flipped the wheel over and voila, the dish was just as bad but reversed .

When I trued it up, the spokes on the "need tighten" sides wern't particularly loose, and those on the "need loosen" wern't particularly tight.

I like the idea of some kind of spacer having been present once.