Vegans/Vegetarians, need to ask you a question?

I need your help. Have you ever bought foods that were labeled vegan or vegetarian, but come to find out, they weren't? For instance, they had casein, cochineal, gelatin, vitamin b12, etc.? I need to know because I'm writing a paper on how some of these foods do have these animal by-products in them, but I only have a few that have vitamin b12 listed in the ingredients. I found soy foods with casein in them, but those don't exactly have to be vegan or vegetarian foods.