I have strong foot odor, and so wear socks with anything but moccasins and open sandals. The socks absorb some of the perspiration and odor. Plus I shake in lots of foot powder intended for odor control, except not with the open sandals, though I may lightly powder my feet first, anyway.
So sometimes the sandals get bad, and if Fabreze and putting them out in the sunlight and fresh air won't solve it, I get rid of them. I have this horror that I might be somewhere, worst if it's at friends, and my sandals are reeking. And sandals are like what I wear about 80% of the time here in Florida. I just buy fairly inexpensive and replace them often.
At the same time, the open nature of the sandals helps to reduce the odor from forming in the first place, which can involve bacteria I believe, so you might look at sneakers that are especially breathable, and not wear them all day. And then when you take them off, peel the tongues back for a good airing, taking out the removable sole insert, which most have. And wear socks, at least the ankle kind.