Do you know how many people touched your can of soda before you did?
Just about everything about the food industry is heavily regulated by the FDA to insure food cleanliness and safety, but somehow they don't seem to care much about the cleanliness of soda cans.
Think about it, long before you put a can of soda into your mouth, that can has potentially been touched by quite a few people, and it's likely been exposed to a variety of dirty places, yet there you rarely see any sort of seal on soda cans. Isn't that strange?