Actually, the problem is that pseudoscience resembles popular science.
Let’s say you have a book or documentary. It goes through some evidence, maybe following the people studying it, maybe experiments, maybe just ideas and what’s done with them. The it comes to conclusions that are shown to follow from these. Say, “We considered these known facts and came up with the idea that things might be like this. Then we ran this experiment and got these results, proving our conjecture.”
Was that book or document a popular representation of established science (or maybe something new we can’t be sure about yet), or a bad, pseudo-scientific argument for conclusions that really don’t hold? You can’t tell without background knowledge and/or understanding of the field. Something that’s complete nonsense and “proven” in ridiculous ways and contradicts everything already known might sound equally believable as the best-proven thing.
Popular science presents things simply and tends to skip a lot of the scientific process that was needed to establish all this stuff. Pseudoscience just skips it altogether. With pseudoscience, the entire process might be nothing much more than what you’re shown in a single book or documentary. (There was probably more work behind it, but I mean there’s not substantially more reason to believe it than given.) If you watch a documentary or read a book about real science, the process presented there might not be any different from the process presented if it were really pseudoscience.
Of course, it’s also possible for popular science to go into more detail and stress how complicated, slow and just plain big the process is if we’re talking about real science. It probably should do that often enough to give people an idea. Fortunately, not all pseudoscience uses the means that can gain it even this appearance of credibility: lying. The book Dianetics by L. Ron Hubbard is now the basis of the religion of Scientology, but it started out as a fake science book, and the author keeps repeating the stuff he’s saying is established by previous science (when it’s not) or has been proven repeatedly in his own extensive experiments (of which there’s no record of his having performed, and anyway many claims are untestable).
We can work to increase awareness and make our works of popular science better, but it looks like there will always be enough ignorance that people can’t tell pseudoscientific works apart from them.
Just for the record, by the form “pseudo-scientific” above I mean “pretending to be scientific”, whereas by “pseudoscientific” I mean “relating to pseudoscience”. Yes, the distinction is almost nonexistent, but it was enough to make me want to use different forms.