Hello Michael,
I've just checked and don't see any spam on that feed right now. Of course, that doesn't mean some spam didn't show earlier!
There is a lot of spam posted to this forum. Most of it is filtered by the Akismet plug-in, and I manually delete posts that go through when I check the forum, which is usually several times a day (the checking, not spam going through). I actually have to manually remove spam about two to three times a week, it's not very intensive. Fortunately, Akismet usually gets rid of the most distateful spam.
What type of spam, and with what frequency, do you see in the RSS feed? The reason I'm asking is that, possibly, your feed reader keeps RSS entries that disappear from the feed, and that's why you end up seeing them.
If you let me know what RSS reader you are using, I may have a hand to test and possibly address it.
The problem with spam is so bad these days...