Why does my boyfriends semen smell like something dead?

Semen may have an odor, sometimes slightly oily of vaguely fishy. It will often take on the smells related to what he has been eating, so look at his diet before making choices. Vegans often say that Vegan men have less body odor and specifically less odor in their semen & that makes some sense, rotting vegetation doesn't smell as bad to most of us; as rotting meat protein.

If the odor is VERY strong, it may be a sign of infection or an STD, Strong genital odors are almost always associated symptoms of all STD's because infection is rotting protein!