OK, I know it's a strange question, but I'm intrigued.
Several times now I've noticed a funky, rancid smell on the sleeves of my t-shirts. At first I thought it was spit-up from my baby, but she hasn't spat up in a while so I know it's not the case. Then I realized the smell comes from a spot that usually gets wet from my leaky milk. (Let's say I'm nursing her on one breast, I have my arm close to the other breast, which leaks during let-down. The leak goes through my shirt and onto my sleeve.)
So I've determined the smell is from leaked milk that dried up on the sleeve a few hours prior.
Why does it stink like this!?! Is my milk stinky?!?!??????????????
PS. I'm not talking a huge amount of leakage. Also, it's a clean shirt fresh from the drawer the same day.