Changing out your shoes daily will reduce the smell issues. Never wear the same shoe two days in a row.
Gel inserts help a lot as mentioned above.
Changing shoes out by activity will help a lot also. A nice pair of hiking shoes for rough terrain, sandals for in campsite, mesh/canvas slip ons for driving, etc.
Stock up on baby wipes. Every time you change/remove your shoes, give your feet a good wipe. That will help reduce dirt building up in your shoes.
Fisherman style sandals offer a bit more coverage while still allowing air to circulate (see photo posted above - that's a fisherman style). Water shoes work great for beaches, mud, etc. Moccasins, etc., can workk well for driving. Many shoes (even leather) can be tossed in the washer on occasion if they get extra icky - just let them air dry.
But i'll repeat that the best and easiest solution is to never wear the same pair of shoes two days in a row.