This Valentine's Day -- like every Valentine's Day -- Victoria's Secret is pulling out all the stops with an ad campaign that dubs the event "Bombshells Day."

Urging boyfriends and hubbies across the country to "forget the flowers," "cancel the reservations," and "lose the card," VS's implication is clear: You should instead do your Valentine's Day shopping for lingerie at VS.

What Victoria's Secret isn't telling you is that for some shoppers, Valentine's Day is no longer what counts. Feb. 14 has become the anticlimax, while the main event is Valentine's Eve. Feb. 13.

Or, as it's become known, Mistress Day.

They are "the 35%"
Earlier this week, the somewhat scandalous website SeekingArrangement.com (which bills itself as a marketplace for "modern gentlemen" seeking "sugar babies" -- yes, seriously) published the results of a survey on Valentine's Day spending habits among married men. Specifically, the survey asked 2,210 married men whether they spend more Valentine's cash on their wives, or on their mistresses.

The answer: Fully 35% of married men said they spend more on their mistresses.

Note that this does not mean that 35% of married men actually have mistresses. It means that when polling the population of SeekingArrangement, 35% of that admittedly adulterous pool of pollees spend more on their mistresses -- which sort of stands to reason. (According to Statistic Brain, the actual number of "married men who have strayed at least once during their married lives" is only 22%).

Cashing in on adultery
Another revelation of the SeekingArrangement survey is where, exactly, married men are spending their money. Here, we've got good news and bad news for the wives of those men.

The good news? Last weekend's Saturday Night Live skit notwithstanding, not all American husbands do their Valentine's Day shopping at the last minute, going through the motions, and just tossing "some dumb little thing" from CVS in the shopping cart. Rather, most married men at least try to make an effort. Sixty-seven percent of those polled by SeekingArrangement patronize L Brands (NYSE:LB) subsidiary Victoria's Secret when shopping for their actual wives. Twenty-one percent head even further upscale, shopping at Nordstrom. That's the good news.

And the bad news? These wives could have done better (in more ways than one). Turns out, when shopping for their mistresses, straying husbands wander even further up the expense ladder. Forty-three percent of those polled patronize privately held (and discretely online) retailer Agent Provocateur Limited for high-end lingerie. Thirteen percent spring for shiny (and pricey) baubles from Tiffany.

As SeekingArrangement explains: "the 'Other Woman', the one the wife doesn't know about, deserves some novelty." For mistresses at least, a Whitman's Sampler just doesn't cut it.

Rich Smith has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.