Retrohaling is NOT the only way to get the desired results from olfactory senses. Furthermore, if you really want to get scientific with it, orthonasal actually stimulates more.
NCradioman, we have had this same discussion before:
http://www.cigarasylum.com/vb/showth...light=olfac%2A
It's not a matter of if it works. It's a matter of how well it works. Especially in some people with sensitive sinuses, or allergies. Another aspect of the problem, is that if the mental link of that "flavor" is not there, no amount of retrohaling will increase the chances of naming that flavor.