Yesterday I found a 20c with an off centre strike, the rim is very wide at one end and on the opposite is almost non existent, would this qualify as an error, Here is a picture of the little sucker.
(http://i141.photobucket.com/albums/r53/patchy001/IMG_2387.jpg) (http://s141.photobucket.com/user/patchy001/media/IMG_2387.jpg.html)
I see plenty of offsets and usually only keep one if the thinnest part is less than about 20% as wide as the opposite edge.
Yours is a little above that (arbitrary) rule but, worth keeping; and now your task is to find one with more offset.
I have never been able to establish if there is a recognised guideline as to what is worth keeping. Everyone seems to have a different idea.
Of course, the target is one with no rim width at the thinnest part but that is rather rare!
Jeff
After the discussion we had a while back on this, I've been tossing mine back. Just in this sack of $2, I must have seen a hundred or more like the one pictured so far.
Its not one I would keep.