Can't get the stink out of your gym socks? It's probably because you're being too nice to the environment.
A new study has found what's to blame for the smell of dirty laundry, and why the odour sometimes lingers even after washing.
Eco-friendly cold washes can struggle to kill the organic compounds created when sweat meets bacteria that live on our skin, according to research published last week.
"The need to conserve the environment by reducing the wash temperature and the use of biodegradable washing products have grown in importance in the new millennium, making this type of research more high-profile," says Professor John Dean of the University of Northumbria, who contributed to the study.
Scientists studied eight pairs of socks, worn inside shoes for 10 hours and left in a bag overnight, and shirts belonging to nine men who took part in a five-a-side football tournament.
The study found six key compounds and their scents:
Microbiologist Siouxsie Wiles told Paul Henry on Monday sweat itself has no scent.
"It's when it's acted on by the bacteria that live on your normal skin that they convert it into smelly things."
And while some of the scents don't sound so bad -- who doesn't want to smell like fruit? -- Dr Wiles said when combined, they might not work so well.
After washing with biodegradable laundry powder at 20degC, the clothes lost some of their stink. But don't go setting your washing machine on 'hot' just yet.
"They only apparently had one person whiff everything," says Dr Wiles.
"Everybody will have a slightly different idea about what smells good and what smells bad."
The researchers hope that by identifying the compounds that cause dirty clothes to smell, laundry powder and washing machine manufacturers will develop products better at eliminating them.
"At lower washing temperatures, these can be difficult to tackle," says Prof Dean.