I got one parking citation but contested it and didn't have to pay the fine. It was the last day of school a couple semesters back and my car (with my semester parking sticker attached to it) was in the shop so I took my mom's. It was my last final, I was only there for about an hour, and getting a one day parking permit never even occurred to me. I walked out to the car just as the officer was finishing up the citation. He had already keyed in the electronic info so it was too late for him to rip it up, but he was really nice about it and told me exactly how to contest it.
When I was going to school for auto mechanics some years ago we could bring our vehicles to work on and get a temporary parking pass for free from the shop (one day only). I just covered up the date on the pass and used it for months until I finally got a ticket for $15 or $20 I think... after about 50 days of free parking that usually costs $2-5 a day The worst part is that was my last day of school when I got the ticket