Philosophies Predicated on Falsehoods

As I read more philosophy from the early 20th century and prior, I find myself confronting a serious issue:

How much should one invest in theory and thought predicated on objectively false scientific information? Is there anything to be gained from a philosophy based on false assumptions like nihilism, for example? Can we use them as mere historical and stylistic tools, or does this just promote the possibility of the ideas within being perpetuated and adding to scientific illiteracy?

As someone confident is the ability for scientific thought to reveal astounding truths, not just facts, it seems dangerous to present such philosophies without a strong and clear disclaimer. However, the challenge of analyzing these texts without identifying with them can teach the kind of creative and critical thinking that any studies of the humanities is best suited for. Perhaps the danger I'm so worried about is essential to getting the most out of this practice. After all, how else can you identify flawed theories and information if you've never had to sort it out before?