I come from a farming family. Over 50% of my uncles are still in the farming business. I guarantee you that they have never worn overalls out to eat, to a sporting event or any other social activity.
This is not a "farm" or "agricultural" issue in my mind. This is 100% a fan-attire issue. If I had said that I found the gorilla suits to be in poor taste, would all of the zoologists out there have a problem with that?
The biggest problem I have with the overalls is that they are Iowa's "thing." And, yes, I do view most of the Iowa fans I've seen wearing these as rednecks (not rednecks as in they are farmers, but rednecks as in they have probably never lived on a farm, but are classless yokels with confederate flags on their pickup trucks that are never used to haul anything).
If you want to emulate Iowa fans, that is fine.
If everyone wore maroon and gold plaid flannel shirts and earflap hats, that would be unique to Minnesota and I wopuld applaud it. Or gold hockey jerseys. Or gold fishing hats and waders. Just not some rip-off of a style that Iowa has already claimed.
Personally, I choose to wear a gold Minnesota hoodie and a gold ballcap - that seems to work well for me.