If the smell occurs through out the winter and tends to disappear in the summer months where humidity is high, I suspect it's a microbiology question. The reason: hands are very dry in winter months, so people are constantly fighting the cracked skin with lotion or ointments. Best guess: the smell must be due to bacteria that breakdown the dead and skin give off chemicals in the process. Same process as underarm or foot odor. Our skin typically has bacteria residing on it, just like you have them in your intestines, and they perform necessary functions like breakdown of toxins. Winter dry causes a "bloom" of these bacteria because there is so much for them to feast on. Hand cream can likewise feed them. Use a quality soap with triclosan or other antibiotic and see if that fixes it.