I’m sorry about the outward sophomoric feel to this question, but I believe there should be no question off limits in the battle against ignorance.
Lots of kids (and some adults) have been known to eat mucus from their noses. And of course, it’s really gross and socially unacceptable and we tell kids (and some adults) not to continue this habit.
Seeing as “snot” traps dust particles and all other such things that shouldn’t get into your lungs. Those become the “boogers”. As for not being good for you…well…they most likely won’t hurt you…unless you eat them in public of course.
Prolly not unhealthy. A lot of snot runs down your throat anyway–the famed post-nasal drip. As for the dust and grime in boogers–I suppose the stomach acid neutralizes it.