The Riddler is Back

I'm often seen around a lot, referred to many ways,
See me black and you may find misfortune haunts your days.
Tell a thing, that should have been kept quiet, to all around,
Then look inside the sack, there I'm no longer to be found.
Nosiness, prying, snooping, leaves me fearing, full of dread,
For all these things are likely to see me soon lying dead.
These clues combined should start to give a picture, an idea,
Of who or what I am, so can you tell me? Is it clear?