I was checking out one of my company's website's Webmaster Tools to analyze the cause behind some soft 404 errors and discovered that a few of the older errors had affiliate mp referral tags listed as the relative URLs. Since these are older problems and I don't seem too many of them coming up in the last few months I don't think it's still a problem. I'm just curious if it's possible to cause a soft 404 by improperly copying the campaign or referral tag into the URL.
In some MVC, campaign trackers can soft 404 during a platform side route/redirect even if the campaign rewrite on url was successful. I can think of one popular ecom platform that does this causing false 404 positives on every single tracker rewrite it makes.
It can straight break the redirect too if its a software side thing. If the page is generated from query, and query fails from misunderstood URi, it could result in a header/footer loading a blank body (not even a 404) in which case google would think its soft 404.
Can you log your requests/rewrites to see whats up or would that crush your server?
Yes, it is possible. Every parameter you add to URL makes it different from the primary. So, you should be accurate while adding tags or other parameters to your URLs.
Agree it is possible, though incorrect URLs should return a true 404 and not a soft 404. So I would investigate how your server handles incorrect requests.