I actually did a stint in an anatomy lab, and formaldehyde does not smell nice, to say the least. But, that is nothing compared to the smell of an unembalmed (ie rotting) body. There was a med student of some stripe who needed to dissect an unembalmed body for some reason and kept it in a sealed bag most of the time. When the bag was open and you happened to be anywhere near it, you didn't just gag: you gagged and you knew, immediately, that you were smelling literal death.