In reply to James Malloch:
I've been having a real problem after a few long, hot humid days this summer. The only word to describe my shoes was putrid. It was quite embarrassing when I went to the wall for midweek training session, I tried a lot of remedies, hand washing, those little smelly balls etc but ultimately a can of dettol all in one spray (it's antibacterial and suitable for soft furnishings) from the supermarket has worked wonders.
If I had the shoes from new again I'd use this from the start it's been great I just leave it in my gym bag with and spray them as soon as I finish my session.