We had the same smell issue every time we turned our dishwasher (KitchenAid) on and it's embarrassing to admit we were dumbfounded for years without figuring out the cause. We raised the issue twice with two different plumbers, but neither plumber could find any problem to account for the smell each time we ran our dishwasher and once the diswasher had been running a few minutes, the smell would disappear anyway.
Eventually, when we had our old dishwasher replaced with a modern [https://wisepick.org/best-portable-dishwasher|replacement], we assumed (or hoped) the issue with the disposal smell each time we had run the old dishwasher would be resolved too, but we were wrong. We got the same issue.[br]
In the end, it was the drain line that caused this. I had it in a loop and it just reeked every time I fired up the dishwasher. Dirty water just sat in the loop and would reek when I turned on the dishwasher and it did it's initial drain line purge. Smell was bad enough I had to open windows. So I shortened the drain line and adjusted it more like [https://www.askmehelpdesk.com/attachments/plumbing/33283d1286112203-water-always-coming-air-gap-when-bypass-dishwasher-wont-drain-high-loop.jpg|this], and the problem went away.[br]
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