Most bark based mixes, however, are designed for *epiphytic* orchids, or
orchids which grow on other plants. Such orchids need their roots to
dry between waterings (as a general rule) and tend to break down (rot)
when kept constantly wet. However, there are some mixes which are
"designed" for the more terrestrial kinds of orchids--paphiopedilums,
and phragmipediums (some paphiopedilums are neighbors of some Nepenthes
species on Mt. Kinabalu), but unless you know what such a mix should
look like, or what it should be made of, I would be very careful about
repotting a lot of plants in it.
It is always a good idea to find out what sorts of things your plants
need (acid/basic conditions, water retention, longevity of mix, etc.)
then see what sorts od media, or combinations of media will fit the
bill--always with an eye to your specific growing conditions (I grow
under lights in my apartment, and I have trouble keeping the humidity
high enough). Then experiment with different mixes (on maybe one or two
plants per mix) untill you find one which makes you and them happy.
Good luck,
Jonathan