I'm not sure where y'all are going with the discussion about metal-on-metal. The arrows that I added to this photo are pointing to some munge build-up around the lower fork clamp. While it kinda looks like rusty smegma, and there may be a little bit of rust in and amongst that wonderful collection, it's not something to freak out about. Spray it with wd, get a rag up, in, and around where the slider goes into the clamp and wipe it off.
As for where the fork goes through the fork clamp, there's not, and there's not supposed to be, any kind of "seal." The forks are held in the clamps, metal-to-metal. And guess what, over time it's entirely possible that very, very slight amounts of rust can accumulate under there. So very slight to the point of not being worth mentioning. No where near enough to even think about. What you'll typically see is a little band accumulating where that smeg is now.
<edit: on second thought, y'know, I've worked on a fair number of forks over the years. Where the fork goes through the clamps, it's such a complete metal-to-metal contact that I don't recall ever seeing anything that I'd call rust under there. Of course, I'm working on very few synapses at this point in my life, so there's that.../edit>
Now there are, and there are supposed to be, seals where the sliders go into the lowers. You can easily see those, they're black on our bikes. If those fail, you'll know because there will be oil leaking from them. There are seals there because, well, if there weren't it'd be a real bear to keep the oil where it should be and the forks would make a really nasty scraping sound as the two parts rubbed back and forth as you rode. And that would not be good.
So, if you really wanna get uber fussy and chase every last vestige of rust from your forks, you'll have to undo the clamp bolts and allow the fork sliders to move up or down to clean that stuff off. Personally, I wouldn't bother until I did a fork service.
As always, YMMV, standard disclaimers apply, not valid in the state of amnesia...
