Well, I never saw them, but I will need to investigate. I just downloaded Firefox on my computer at work, and there were no offending bookmarks. Probably something specific to my laptop at home, and not endemic to Firefox. I'll check it when I get home.
Nobody should assume, just to make it clear, that you've been visiting salacious websites when using IE - it's entirely possible that some website you visited surreptitiously placed those bookmarks in IE without you even knowing about it.