How should a Christian relate to pseudoscience? 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.)
The Bible advises wisdom, not naiveté: 

1 Thessalonians 5:20-21 (ESV):


  20Do not despise prophecies, 21but test everything; hold fast what is good.


Proverbs 2:9-11 (ESV):


  9Then you will understand what is right and just and fair—every good path. 10For wisdom will enter your heart, and knowledge will be pleasant to your soul. 11Discretion will protect you, and understanding will guard you. 


Although the scientific method, properly applied, is simply a rigorous way to test everything and hold fast what is true (note: not necessarily good, but similar in spirit), one can decorate all sorts of whims and falsehoods with the appearance of science.  Pseudoscience delivers no more wisdom and knowledge than superstition simply because it pretends to be science; you have to actually rigorously apply the scientific method for it to work.

Thus, Christians should adopt the same stance towards pseudoscience--that it is not knowledge, not wisdom, and not to be held fast--as they do towards superstition.