Good questions
Although i think PSA is a load of crap,they don't seem to have any guidelines.Almost seems like no standards exist except for the bunghole that does the grading that day.
I have cracked open every one of my PSA's except for my 16th so far.I look at them with a mag glass and really inspect them.I see many things that don't make much sense.
I have one NM 7 card that has a stick of gum impression and it's marked "stained" as well.
So if that's the case then roller marked cards should grade just as high or higher if near flawless otherwise in my opinion.
As for miscut cards grading NM i think is a real push.I think that even EX cards should have be cut to dispaly well and contain decent corners,A card that has been cut with a tight boarder containing no white edge at all should grade VG+ at best.