Only time I can remember where I've seen a dead person was on an autopsy (part of a anatomy course at uni). But they had good experience with first timers, so they knew what to do to make it easy on us.
When we got there they had already covered up the face, and opened the chest and cranium. They said that seeing when the chest is opened is the worst part for first timers (highest faint rate). After that, the subconcious usually think "dead body" instead of "dead person". And then it's more like a real 3D version of an anatomy book, than something gross.
It didn't bother me at all, it was just interesting. However, if I see pictures or film of a real life surgery or someone that is badly hurt but alive, it's
a lot harder. (And beeing there would of course be even worse.) I think it triggers some switch in my head saying "if someone makes an error now, it will have serious consequences", and that's of course much less of a problem when the person definitely already is dead.
One thing about the autopsy though. The room smelled rather good. It's of course well ventilated and cleaned, and they have stuff there that smells good to counter any odors. But there was something familiar with the scent
When I came home to the "corridor" (~=dorm), I realized what it was. One guy in the corridor used a mens perfume that smelled just like it. I didn't want to spoil it for him, so I didn't tell.
"Hey, nice perfume. Btw, it smells like the local morgue."