This experiment design feels pretty useless to me. The T-shirts were collected, sealed in plastic bags, and stored at room temperature in the dark, so

This experiment design feels pretty useless to me. The T-shirts were collected, sealed in plastic bags, and stored at room temperature in the dark, so bacterial growth occurred [...] The bags were kept at room temperature (20°C) in the dark for 28 h. Bad experiment, IMO. This is not a remotely useful approximation of what happens when you are actually wearing and using the clothing. It's more of a simulation of what happens when you accidentally leave wet sweaty clothes in your gym bag, or are forced to wear sweaty clothes for multiple consecutive days without a wash. (It certainly be nice to have fabrics that could survive such conditions without stinking, I admit) When actually wearing synthetic "moisture-wicking" fibers, I find they stay much fresher smelling as long as they are exposed to air so that they can actually do their job by encouraging evaporative cooling. As opposed to cotton, which soaks up gallons of sweat and takes ages to fully dry. Remember, fresh sweat doesn't reek -- that's why you don't smell bad in a sauna, with fresh sweat pouring out of every pore. It's stale sweat that reeks. Specifically, it is the waste products of bacteria living in stale sweat. That is what eventually smells bad.