DISCLAIMER: dirt and debris do find there way under fork seals and there are a number of tools out there to clean them one being a simple playing card. That being said don't be left with the impression that if your forks are leaking that its only a small piece of crap under the seal. Fork seals do wear out and dirt under them is sometimes the catalyst but there are a few things that wear seals. Not only that but the bushings inside the forks are the internal guides for the tubes. They are coated with Teflon and wear out too. if that happens as it typically happens on a 2-5 year basis the forks wont function well and the seals new, old or clean wear out too. One other thing is fork oil eventually wears down and ends up dirt, very dirty in fact. That is sometimes why the other two parts break. So in conclusion do clean your fork seals particularly if you ride off road but don't assume that it means you don't service the seals fluids bearings and bushings at the factory scheduled intervals.