I would say not usually for orchids if they are houseplants. In fact misting is actually not as helpful as you would think in the average dry northern house. It fools the plant into thinking high humidity is here to stay, and the plant's surface drys out faster than the stomata (pores) on the leaf surface can close; which can result in a net loss of moisture to the plant. Some have had anecdotal success with the extremely diluted brands of fertilizer that may be more suited to misting (but not so helpful as a main fertilizer), like VF-11.
