I don't think you can lump all Iowa fans into one bucket. At least year's game we had a tent setup for tailgating since it was raining. We saw a few ISU fans walk by talking (don't remember what they were talking about), and one from our group invited them up to the tent for some good-natured rivalry talk. They stuck around for about 20 minutes, had a beer and a brat with us, exchanged some laughs, and then they went on their way in the rain.
Of course there's going to be people on both sides that act like idiots, but my tailgating crew has always gone out of our way to be respectful to the opposing team's fans.
We've done the same for many other fans that visit Iowa City. I remember tOSU fans being the most respectful and appreciative, probably because they knew they were going to wipe the field with us. I seem to remember Wisconsin fans being the least likely to get invited back to our tent.