LOL! N-acetyl cysteine should reek of sulfur. The cysteine molecule has sulfur in it. NAC is used in medicine in huge doses to treat acetaminophen overdoses. It's also used to break up mucus in cystic fibrosis and to treat other toxicities. You can always tell what patient is getting that treatment by the stench emanating from their bodily fluids... So, yes, your N-AC is normal.