Anyone who has ever smelled the "aroma" of a dead body, would NEVER forget the smell of Putrefaction. And for anyone who has never experienced it previously, they would certainly look for the cause of the pungent smell.
That having been said, if this DB had been in the compartment since November, 2013, and wasn't found until May, 2014, is troubling, to say the least.
We used to put dabs of Vicks in each nostril to mask the odor. That and a very strong cigar, are about the only way to tolerate the smell.