Why don't you put it up on eBay as a Special Edition Soft Focus SL66 that has been known to have the image of the Virgin Mary show up in negatives that include large amounts of blank sky.

Other things to check....

What aperture do you shoot at? Try taking the same picture at different f-stops and comparing to see if there isn't something revealed by that. Perhaps they will be sharp at some apertures but not others. Are you using a 220 or 120 back and does the film match the back (e.g. are you putting 120 film into a 220 back)? Was theu tester-guy's laster our of alignment<g>? Are you wearing galsses when you look at the prints?