well at my sqn we had 3 people kicked out due to the prescence of coke in their systems during a random drugs test.
bet they wished they had waited a couple of months before getting tested....
from a personal point of view, the last thing i want to to be working next to someone who is whacked out of their head and not knowing what they are doing. i have never tried or would ever want to try class A drugs, just working with someone whos is a bit hungover is bad enough, but i would rather work with them than someone who is drugged up!!!