Americans (in particular..) are way, waaaay over obsessed with laundry/clothes-washing, etc. Merino wool has anti-microbial properties, as do most chamois creams. Keep your body clean and there's no reason to wash merino after every wearing. Of course, the clothing/fashion industry would prefer you wash everything as much as possible, to wear things out as fast as possible, so things need replacing as often as possible. Not to mention the water and energy usage excessive washing consumes. But to each their own- I'm comfortable with a sniff-test being a guide, others are more comfortable with daily laundering.