In article ,
John W. Wells wrote:

Had to remount the dowel so that it "looked right," even though it was
far from level!

For reasons like this it's often better to just "eyeball" levelness!
Hanging pictures, for instance.

Oops; forgot to respond to this. Yes, most homes are not level (walls
are not square or flat) and things do have to be eyeballed, but I like
to see where level is, first. If nothing else, I want to make sure that
the parts of the hardware are level with each other, if not "level"
level.