When I got to Crappy Tire, ah, Chinese Tire, ah, Canadian Tire and I cant see what I am buying, I waltz over to the hand tool section and use snips or whatever to open it up. A young lad saw me doing this one day and asked what I was doing. I said, "Not buying a pig in a poke." He had NO clue of what I was saying. He told me I'd have to buy it before opening it. I said, "You had better get the manager here right away." and I proceeded to open it.
I have had more than one clerk say I couldn't open a package before buying the item. I ignore them. If it's an item with a safety seal, I take to the checkout and open it there before I buy it. Pisses them off but I don't care.