Occasionally I get armpit odor, only on my left side though. The smell can be quite intense as others have said like ammonia big time. Not really sure what causes it, maybe diet or stress related but its so intermittant I cant tell. I do not use any deodorant nor have I used any for quite a few years. Baking soda has always cleared it up instantly. I'll shower and wash with soap (no dye or scent) and still be able to smell it on the left side. Once out of the shower and dry, I take 1-2 tsp of soda and lather it up while my hands are wet and apply to air dry. The smell gets more intense for a few seconds and then its 100% gone, usually for 48 hours or so. I might do this routine for a couple days and then forget about it for weeks/months until I notice the odor again. Wish I knew for sure what was causing this!
I have found out that in most cases the odor is cause by bacteria. Kill the bacteria, odor gone. Alkaline soap with baking soda & vodka will kill the bacteria. Then put on some calamine lotion (zinc) in all the places that collect moisture. Stop using deodorants and anti-perspirants, they are very bad for you. Also wash all of your cloths in Borax, an all natural laundry detergent and never use fabric softeners, they leave behind chemicals on your skin and help cause the stink!