I inspect as many as needed until I find one that I am satisfied with. But I don't ask for multiple bags to compare with, my SA just retrieves them one at a time from the stockroom for my inspection.
With my epi Alma bought years ago, I rejected even when there's just a tiny white speck on the black epi leather, it probably will come off with light scratching with a nail / wet cloth but I'm not going to try doing that in the store, so I still pointed out to the SA and rejected it. I have also recently rejected a canvas bag that had a 2cm rip in it, like it had been accidentally cut with a box cutter. So definitely inspect inside and out, top to bottom!
With my epi Alma bought years ago, I rejected even when there's just a tiny white speck on the black epi leather, it probably will come off with light scratching with a nail / wet cloth but I'm not going to try doing that in the store, so I still pointed out to the SA and rejected it. I have also recently rejected a canvas bag that had a 2cm rip in it, like it had been accidentally cut with a box cutter. So definitely inspect inside and out, top to bottom!