Shoppers Drug Mart

I was trying the "testers" on my arm to see the shade of the lipstick when the woman working told me that it's not fair for the other people if I do that.What are the testers used for then? It put me in a bad mood so I didn't buy the lipstick & paid for my other stuff. I don't want to go back to this store again even tho it's very close to my place