to be avoided at all cost
It's a law of nature or something that the last thing poured out of any box of breakfast cereal will be a variable quantity of very small cereal particles. Cereals containing vast amounts of sugar are the most likely to produce vast amounts of such cereal dust, but in my experience, nothing can even compare to the horror that is the cereal dust left behind by Lucky Charms. The coating of the brown bits and marshmallow flakes unite to form an unholy alliance that when added to milk, creates a substance that most closely resembles a really sugary concrete. If you are one of those who likes to drink the milk left over from your cereal, trying to drink milk from the last bowl of Lucky Charms will only make you grimace as you experience a grittiness that should never be associated with dairy products.
Consider yourself warned.