My shoes and boots and it helps alot.
The shoes including expensive leather shoes on this kind of question his advice comes from gentlemans gentleman one of question his advice on occasion.
I bet the insole can be removed. Peel that stinky thing out and replace it!
You can find shoe insoles at sporting goods stores and many shoe stores. Then make him put foot powder in his shoes every time he wears them. I play sports and this really makes a big difference in keeping shoe stink at a minimum.