I look at it from a viewpoint of I'm buying these for me and therefore how they look in the pages is of most importance. Small creases that you have to hunt to find don't bother me, but severely rounded corners do, but a dinged corner not at all. The gloss is important and mis-cuts are a no-go, but slightly off center I can deal with depending on the year. In the tobacco cards I have some with pencil writing on the back and also a couple with pinholes and because they look great in the albums I have no intention of replacing them anytime soon.
Depending on the year I am very flexible with any cards. As an example if there is a Barry Larkin that is numbered to 10 and it is not in NM or even pretty rough condition it will not stop me from adding it to the collection, but if its a 94 Leaf it has to be in perfect condition.
With the older sets as long as the commons are in good shape it will still look good in the album and then its also affordable even if the stars are rougher.
On a different note I also noticed that it seems as though anything pre-56 is tougher to find in a nice condition for a reasonable price where there are alot of great conditioned late 60s through 80 cards out there