when i go to a photo store that has film and paper, i always open the boxes and sleeves of paper
boxes of film ( and those annoying foil packets ) and sometimes pull some of the 35mm out of the cartridge.
to make sure the film and paper are in there, before i buy it, i don't want to get ripped off.
I try out every match in a box in the shop before I buy them!
"People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.