Although during the season my university athletic facility offers a complimentary laundry service, I find after the season I'm not inclined wash my running clothes, since I have to use a pretty expensive laundromat if I want to do it. I don't need to wash normal street clothes that much since I just wear jeans and a T-shirt, sometimes over and over as long as they still smell good. I have 5 pairs of running shorts which seems reasonable, but with doubles I can burn through them in 3 days sometimes. I don't want to do laundry twice a week in the off seasson. I just don't wash them, and they get start to get ripe as hell and really crusty. I wore one pair for 7 runs without washing, and felt terrible every time I put them on since they were so pungent.
How often do you wear each pair of running shorts before you wash them? It might be a relative thing, like how long you run in them. Maybe there is a formula where we take into account metabolism, volume, and intensity of each run in finding a limit.
Post your experience; keep in mind civility.
"Cleanliness is next to godliness"