The karma system also gives forum posters the ability to assist with moderation. Threads that are really bad drop sub filter before they are nuked by the admins. Threads and posts that are rated up get left alone when we might have otherwise moved them for beign off topic, etc. Once you are up near a thousand or so posts (which is trivially easy to get these days it seems) you personally are pretty much immune to the effects of the Karma system anyways, so the only people it really has a major impact on are new posters, which are some of the primary targets to begin with. It's a system. Like any system, there are people who work to game the system, people who abuse it, people who benifit from it overmuch due to errors, and areas that can be tuned. The administrators are the checks and balances of the karma system. For example, I can at my discretion reset the karma of any sub default individual back to system default 3.00. All administrators can also apply unlimited up or down rates to an account to adjust for "Karma camping" system abuses, errors, or other such karma events. And we do correct things when we find ratebots or karma campers and the like, but otherwise we rarely intervene. It's my board to run, but the overall content, feel, direction and what is liked or disliked and rated as such belongs to the forum as a whole and all the people who post in it. Us administrators can shape and guide that, sometime quite forcefully, but we usually don't, because it annoys people.
Are there Cliques? Sure. Do they have an impact on day to day forum operating and ratings? No. If you could see the rating history of a given thread, you would be suprised to see who does the rating, why, and how frequently. I almost garuntee that the people you think are rating your posts, aren't. We don't care about why they rated it, Their reasons are their own. All I care about is that it doesn't become an attempt to artifically inflate or destroy a base karma across an entire person or thread, it isn't done via ratebots, and if two people want to rate eachother into oblivion that's fine with me.
It really does work pretty well overall, and where it doesn't, we fix it.