For the courtesy Flush to even work AT ALL with regards to smell, you have to flush a little ahead of the game. You have to time the flush so that as soon as the flood gates are opened, the evacuated materials are sucked immediately down the chute.
Also, if you wait too long for the placement of this courtesy flush, not only does it do nothing towards the elimination of potentially offensive aroma, but, it allows the surrounding area (e.g.: the dude in the stall next to you (e.g.: me)) to hear sounds that he can never un-hear.
These sounds may include but are not limited to:
A) Heavy breathing and/or groans and/or whispered "oh my god"s.
B) Plopping sounds.
C) Much fartage.
D) The sound of friction between your back door and
WHATEVER YOU ATE TO MAKE WHATEVER DEAD SKUNKS AND SPOILED MILK JUST CAME OUT OF YOU.
I am one uncomfortable experience away from bringing earplugs and a gas mask to the office.