Mythbusters once did a segment on buying a car someone had died in. They bought a pristine used Corvette, dumped a few dead pigs in it and locked it in a shipping container to bake in the California sun for a few weeks (maybe months, can't remember). Long story short, the smell attached itself to everything. Being a Corvette, even the fiberglass body panels were ruined.
Admittedly, this was an extreme case for entertainment purposes. But you have to consider how little of the vehicle might be useable after such an event. You'd have to replace interior, ductwork, wiring, insulation, maybe rubber/plastic body grommets, under-hood hoses...nothing left but body panels, drivetrain and suspension. You could part it out. But who wants to deal with the health risk of taking all that mess apart? It'd be a hard pass for me, unless I could personally inspect it before purchasing.