Rodgcam, that is an impressive stamp (your 523). Wow!
The pressmen upped their game in the months following the C3 (what with all the fast Jennies, grounded Jennies, etc., not to mention the invert). That centering of the vignette is a wonder.
So from that perfection here is some post-production imperfection:
I offer a Sc. 397 I added recently as I replace used placeholders from long ago....
Fairly well centered and such, but what persuaded me to this particular example after the general curb appeal was the owner's mark stamped on the verso.
I'd known of them in the abstract, of course, but found I wanted this as an example -- just one -- of practices past, something of a conversation piece to have in the album. To judge from my comparison shopping with other MNH-OG, I believe the mark knocked 30% to 50% off the asking price.
I'm curious, of course, about who, where, and when, the owner with the horsehead emblem was, but my cursory searches have yielded nothing.
Do y'all try to avoid them or have you on occasion accepted them?