[glynparson]

Altering is more often than not on high dollar as opposed to just high grade items. Anything where even a grade bump means good profits (though the doctors seem to shoot for 2 or more). Set up at some shows you would be amazed how often your nice cards with a "fixable flaw" get bought by the same individuals. It is not really all that hidden. That said there are plenty of high grade cards not messed with.