I tire of reading these misconceptions, just because they have been feminized doesn't make them guaranteed female just a higher likelihood. It is nature, think about it for a minute.
OK, lets think about it.
To create "feminized" ceed you're pollenizing one genetically female plant with pollen obtained from another one (or at least that's what you're "supposed" to be doing).
If done correctly, in fact there should be negligible chance you get a genetically male plant because neither parent should contain a "Y" chromosome region it can pass onto the offspring ceeds to create true males. Just on a basic genetic level, there should be no way to cross two females to get a male.
Now, as you point out, nothing is perfect. . .in any facility, especially a breeding one where lots of strains are being crossed and ceeds created, there is a chance for stray male pollen passed through the air, or even adherent to someone's clothes, to pollinate a female and contaminate a ceed-run. So there is always some small chance a male could be created accidentally that way in a run that's supposed to be feminized.
Of course sloppy breeders can always mislabel ceeds, or accidentally get ceeds from one run mixed up with another, and thats another way a male ceed could end up in a "feminized" pack.
In my opinion, whether or not they actually do it, breeders *should* be guaranteeing that their feminized ceed packs yield all female plants, if not explicitly, then implicitly. . .that's just basic quality control/customer service. Mislabelled ceeds really would be the breeders fault, and while stray pollen arguably may just be an unavoidable risk of making ceeds, any breeder worth their reputation should own up to that sort of thing and address it.
Other ways this can happen?
After a pack is released from a breeder, an unscrupulous dealer/seedbank employee might steal a ceed by switching it out with a generic one that turns out to be male. I've never actually heard of a case of this happening, but its possible, I guess.
Its possible for someone (maybe not so sober) to accidentally swap ceeds in their collection, or plant the wrong one by mistake, or even just confuse ceeds planted from two different strains at the same time, again, potentially growing a male where a female is expected.
Lastly, some plants that are genetically female can express male-like preflowers and be mistaken for males, especially if the plants are intrinsically hermie-prone. I've been fooled this way myself by a plant that put out "perfect" male pre-flowers right next to a sibling with perfect female preflowers. Assuming for sure that the first plant was a male, I kept it for possible ceed-making, only to end up rather surprised when it turned out to be a female after being put under 12-12!
As to "being in it for the money", in my opinion, its a mistake to confuse the motivations of a breeder with the quality of their work product. Just because someone "loves" the plant doesn't mean that they know jack-poo about breeding or that their ceeds are any good. Conversely, just because someone wants to make a lot of money doesn't mean their genetics are bad. What better way is there to make a lot of money breeding than to provide great genetics that everyone wants to buy and great customer service that keeps the buyers loyal and coming back? One would like to think that the best breeders also do OK financially, though unfortunately it isn't always true.
As a general rule, you'd have to assume that anyone who spends considerable amounts of their time professionally breeding cannabis probably loves the plant AND wants to make money. IMO, nothing wrong with that. Personally, I'm just after the best genetics possible. I don't really care why the breeder in question creates them.