This chart from Wikipedia quite nicely explains what pseudoscience is:
I think it's quite clear from the Bible that we Christians shouldn't give room to superstitions. As pseudoscience is close to superstition, should we treat it the same? What guidelines should be used when deciding whether to believe what some call pseudoscience?
For reference, some examples of claimed pseudoscience (from Wikipedia):
Examples of pseudoscience concepts, proposed as scientific when they are not scientific, are creation science, intelligent design, orgone energy, N-rays, ch'i, L. Ron Hubbard's engram theory, enneagram, iridology, the Myers-Briggs Type Indicator, New Age psychotherapies (e.g., rebirthing therapy), reflexology, applied kinesiology, astrology, biorhythms, facilitated communication, plant perception, extrasensory perception (ESP), Velikovsky's ideas, von Däniken's ideas, Sitchen's ideas, anthropometry, post-normal science, craniometry, graphology, metoposcopy, personology, physiognomy, acupuncture, alchemy, cellular memory, Lysenkoism, naturopathy, reiki, Rolfing, therapeutic touch, ayurvedic medicine, and homeopathy.
(You may assume that creation science and intelligent design are in fact protoscience, if you want to avoid focusing on them.)