I dont know where they get their information from, but putting a goldfish (or any sweetwater fish) in saltwater is a bad idea unless you really know what youre doing. Also, it is only done in extreme cases if the fish has a disease, usually a common form of scale-fungus or parasites. There is medication for this. So dont just go dropping your fish in some kitchen salt "just to invigorate it" because most likely it will die.
This is a great article. What amazes me is the Antikythera Mechanism. If they had this technology 100 to 150 years BC, then what the heck happened in the meantime? Did we all just blank out for 1000 years? Weird.
I guess the only way to keep their numbers down is to wash and replace your bedsheets every day, wash your comforter or blanket every month and use a steamcleaner to clean the top of your matress. Oh and using a vacuum cleaner is a bad idea...:
http://en.wikipedia.org/wiki/Dust_mite
http://nl.wikipedia.org/wiki/Muskusrat