Posted By:
MWMarc --
Yes; I would agree with your last statement. Collections usually contain very, very few altered cards or, in some cases, a significant amount. I would say that it would be fairy accurate to assert that altered cards tend to accumulate in certain circumstances. It is also perhaps interesting to note that nearly every collection we purchase that was assembled in the 1970s or earlier, contains zero altered cards.
I can't give you an exact estimate on the number of altered cards we encounter, but it would be quite small if all cards are considered. If only star cards (say, with a value of $100 or greater) are considered, then the percentage would be somewhat higher. Possibly 2% to 3%. If anything, we encounter far more reprinted cards that are artificially aged.