I have two pair and wear them whenever I feel comfortable looking a little odd.
I tweaked my knee almost two years ago jumping off a retaining wall, and still have some pain and lack of strength on that leg. I have found that the Vibrams allow me to control my balance and this greatly reduces the minor discomfort this injury causes, especially the next day.
I love to play golf and always wear them when playing. The feedback from your soles is awsome for a sport where your feet are planted and you twist while having a weight transfer during the activity. Prior to getting the Vibrams, the day after would always be much more uncomfortable, and frequently I would re-injure my knee, requiring up to a week to get back to stable. Now, I seldom notice any discomfort while playing, and have not had any relapses from swinging a club.
After about 10 days of wear I just throw them in the washing machine along with my other wash. I air dry them, and they don't look any different than when they were new.