I am getting to be the opposite: as long as the card has great centering and is clean and well-registered I am fine with lesser corners or even a slight crease. The vg-ex due to a small crease that looks nm-mt is my favorite place to play in postwar cards. But there are exceptions. If you collect all things 1971 Topps, as I try to, you have to go after OPC cards and you basically will get o/c cards from Canada:
The centering on OPC sucks so bad that I will take lesser grade if they happen to be centered:
The only place I might splurge is on a Hank Aaron (favorite player of the era and all).