The good Ritek stuff has a sweet electrical fire smell to it. The Maxell DVD-R media smells of tropical oils - not the distinct coconut of the TY's, but perhaps more of a guava-mango combination. The +R media smells like toxic death, but it's also good stuff. Most CMC media smells acrid - back to the electrical fire but more bitter; and the Ricohs can resemble microwave popcorn.
Over time, we're going to be able to peg the manufacturer and quality just by smelling the discs! When I smell acrid factory fire smoke - it's CMC and time to get the fire hose and blow that stuff down the street. But I'll sit on the deck with the mango-guava-coconut TY/Maxell party and be happy any day of the week.