Today i have learned that smoking near your xbox can seriously damage the lens in your xbox, and the 'open tray error' is majorly caused by the smoke damage.
yes, smoking kills electronics.
1) smoke residue coats connector edges
2) smoke residue builds up on the circuit boards
3) smoke residue coats trimmer controls
4) smoke residue holds moisture/humidity
so watch out, not only does it affect your own health, it affects your xbox.