A lot of used Thinkpads stink horribly

I work in an IT depot where I work to receive our company's used laptops, evaluate if there's anything wrong with them, and if they can be reused, send them back out to new users or employees who need a refreshed laptop or a loaner or something. I do Dell, HP, and Lenovo, but the Lenovos specifically, the ones with magnesium cases, are almost always rank as hell, and it's always the same smell. I can't place it but it's almost like cigarette smoke, and also kind of like oily hair?? All I can think of is that it's the magnesium of the case itself having degraded and begun to break down chemically due to the heat of the processor, and that chemical breakdown mixed with normal tame smells like dust or skin oil creates this weird, terrible stank. Anyone else experienced this or know what it could possibly be?