No, actually that isn't the truth at all.
Those bad bacteria are present in a special balance all the time in your vaginal flora and something (unknown) knocks the balance out of whack. It isn't just sex or mentstruation although many women notice the odor after those things because the semen and blood alkalize the vagina creating a stronger odor, something happens to cause a die-off of the good bacteria, which are actually hydrogen-peroxide producing lactobacilli species, and letting the "bad" bacteria flourish.
This is NOT a sexually transmitted disease and certainly does not mean anyone is "creeping around". My personal theory from my personal experience is that a lifetime of antibiotic use and eating "dead" food causes BV. Antibiotic literally means "Against Life". It kills the good bacteria along with the bad and the bad bacteria proliferate because there is no replenishing of the good bacteria to stop it.
Good bacteria are available in "Live" food but we no longer eat these things. We destroy our immune systems with our diets and our environments and our lifestyles and the antibiotics complete the chemical soup. By the time my daughter was 2 she had been on antibiotics at least 20 times. By the time she is 16 or 18, begins to menstruate and becomes sexually active, I have no doubt that if left unchecked she will develop BV - Do some study and research, this is NOT a disease for us to be ashamed of. This is a call to action - it's OUR responsibility to educate ourselves about our feminine health!