Douching is not really for a smelly vagina, its for after your cycle for deeper cleansing. Some OB/GYN's dont even recommend it because it may push bacteria back up inside the woman, a good warm bath with vinegar can be sufficient.
Also it may be the frabric of her panties or washing products she is using or it may be a sign of bad eating habits and not enough acidopholus intake. She might need to trim her hair because it holds odors too. Dont just tell a woman she needs to douche, she may go into overkill and make the problem worse...either way tell her and be direct but not insensitive.
Yes, despite what many older women may say (I STILL know some older women who believe in douching), it is not good for the coochie! She probably thinks it's just normal, and keeps it moving...but...that...shit...ain't...RIGHT!
Every women's vagina has a smell...it shouldn't be a pungent one (lol @ pungent), but there is a smell to vagina...just as there is a smell to a dick, and other parts of people's bodies. Usually, around ovulation time, the smell may become more apparent because of the increase in secretions "down there." But, that...shit...STILL...should...not...STINK!
I once messed with a guy who was, apparently, so happy I was clean down there. It made me wonder who in the hell he was messing with before me, and easily killed my "high."
I also knew a girl, in undergrad, whose whole room spelled like pussy...how does one have your whole 6 feet x 6 feet x 6 feet closet-of-a-room smelling like your pussy?!? And not even FRESH pussy! That...shit...ain't...right!