When you are looking for a comic from the silver or bronze age and you want it to be in NM condition but you are tired of buying from people claiming its a NM and when you get it its more like a VF, here are the things to look for.

1) Ask or look at the corners, they are one of the most important things to look for in  NM grade, They must be square with no creases.

2) Ask or look at the spine, make sure there isnt more then 1 or 2 spine marks or dents!

3) make sure there are no staple tears

4) obviously the book should not have any rips, creases, or stains!

5) Look to see if it has a rolling effect to the spine, some books were printed with a slight roll but if it looks creased or if the spine isnt flat it most likly wont get a NM grade.

6) look at the page color, it should be anywhere from white to cream but never brittle.

Look at all these things and always ask questions, make sure what you are buying is what you really want!