I wear my running kit many many times before washing it,and i can't say i have notice that it starts to smell? but maybe thats why i end up running on my own!!!. But seriously i have seen me get away with wearing the same kit for over a weeks worth of runs, before i stick it in the wash.I know this may sound gross.... but why wash it everytime? its only going to get sweaty again and it cuts down on my familys laundry.
However there is nothing better than pulling on a nice clean smelling running top / gear on the morning before an eagerly anticipated race!