Dear lauramari, my underarms are not dark and I know of no one else who said they have dark underarms. I would like to think that the lack of physical hygiene does not cause discoloring of underarms or armpits. May I ask if you've ever shaved your underarms on a regular basis to keep those "weird smells" as you say away? If you do, many factors come into play as to why your armpits or underarms have turned dark. Old shaving razor blades, or shaving paraphanelia that is not thoroughly cleaned or sanitized will cause your skin to discolor, shaving preparation that is too potent or strong for your skin (your skin may be sensitive under your arms),as a result bacteria builds up that can discolor your skin, especially when there have been tiny cuts and bruises from shaving. Bacteria and germs then will have easy access to the underlying layers of one's skin, thus causing discoloration. If, this is not the case with you or others who have this problem; then seek professional medical advice so as to resolve your problem. I wish you success in resolving your problem. Take care.