Leaving washing in the washing machine too long

I hate this. I'll do a washing and then forget all about it. When it comes out of the washing machine a couple of days later there is that funny smell to it. It isn't nasty but it ain't nice either. And you can't even bung the stuff back in again as the smell won't go away - you have to dry the stuff first and then wash it again. Most of the time I don't actually forget about it I'm just too lazy to take it out. Or more to the point - I say to myself - I'll get it later.