Well around where I lived in NY, there were REALLY hilly roads..with 30mph speed limits. Everyone sped on them, whether they exceeded the limit by 8mph or 30mph. And yes, 8mph isn't that much of a difference...but there were so many kids in the neighborhood, and SOOO many damn deer from a nearby nature preserve. So every 2 weeks, they set up a speed trap and nailed many people, including alot of local residents. Yeah it sucked, but in some ways it was to enforce driving at a safe speed to react to deer and kids.
I don't know the specifics about your situation, and I think everyone has had their experiences with speed traps in ridiculous places as well. But there really isn't much you can do to contest the location of a speed trap...whether it is hilly or flat. It is up to the cops/city's discretion as to where to put them..and when they do, all you can do is slow down or get a ticket.
Now as far as getting hte ticket. I'd at least take it to court. You could plead NO Contest, or Not Guilty. I generally say plead not guilty, as almost always, either the cop or a district attorney of sorts will meet with you prior to going into court, and try and bargain down with you. Generally, they will offer a lesser violation. I try to bargain it down to something that isn't a moving violation/no points...and then happily pay hte fine. You may want to check in your state. I know in NY "Failure to Obey a traffic control device" = 2 pts, but in PA it = 0pts. That is generally what they offer, if not reducing the ticket to 0-5mph over the speed limit. It is up to you, but generally that is the route I recommend. Don't just pay the whole thing.