Smelly tennis shoes?

Now here is a remarkable fact. When I lived in California, and especially when I drove down the Mississippi valley on a trip back to the US last summer, I noticed the old problem of bad smell developing in my tennis shoes. Disgusting and ineradicable!

Amazingly this does not happen here in Thailand?

Why?

Years ago as an engineer I used to consult on legal problems arising from mold in houses. Erin Brokovitch was my client! What I learned is that mold grows best at moderate temperatures, not where it is very hot. Even the mold can't stand Bangkok in the hot season!