I'm not sure if it applies, but look at how I handled looking at inspect target's items in my addon. Far as I can see, it does not cause taint.

https://github.com/Ketrel/BetterItemPreview/blob/master/BetterItemPreview/core.lua

Hi,

Thank you for the feedback, but your addon will also taint, as will any addon that overrides HandleModifiedItemClick. If you reload UI, inspect someone and Ctrl-click one of their items (without first explicitly opening the dressing room), the dressing room will be tainted, and you will not be able to Link Outfit -> Copy to Clipboard.

You are right, I've never used that feature and didn't notice it.
(Though I can still perform the function with mine, I get the taint error, but it still works, possibly because I call the original function? Though after that, I need to reload for any further loads)

Do you mean you actually get the outfit copied to the clipboard? What happens to me is a message is printed saying it got copied, but actually did not.