I too have seen Barf detergent! A friend of mine bought some in Dubai.

Many of these, however, are sort of urban legends that grow up when people try to show how much cleverer they are than people who do marketing for a living. For example, the no va story is completely false, and is spread largely through marketing textbooks. In fact, the Nova did fine in both of its Spanish-speaking markets, Mexico and Venezuela. The mistake between "nova" and "no va" is one no Spanish speaker would make, for many reasons:

(1) in Spanish, "nova" means exactly the same thing it means in English: an exploding star that suddenly becomes visible and thus is a new star in the heavens. It's a perfectly viable word, and there's no reason to misconstrue it as anything else.

(2) Spanish is a Romance language, and the etymology of "nova" is even more obvious to the average Spanish speaker than it is to the average English speaker. Even if they didn't know the astronomical meaning, they'd guess it meant "new."

(3) "No va" does mean "no go" in Spanish, but Spanish-speakers don't use the word "go" to describe a car's operation; they would say "no camina" or "no marcha." "No va" suggests something that will not leave rather than something that does not work!

(4) The best-known brand of gas in Mexico, marketed by the state-run petroleum monopoly, is "Nova."

(5) People who speak Spanish are perfectly capable of distinguishing between "nova" and "no va," in exactly the way we English speakers can distinguish between a person who is is "notable" and a person who is "not able."

Similarly, matador does indeed mean killer, but "Matador de Toros" is a quite formal term is Spanish, like "race-car driver." In the context of the bullfight, he is always known simply as the "matador," just as in the context of a race, we speak of drivers, not "race-car drivers." Spanish-speaking people associate the word matador with bullfighting as well as with other kinds of killing, and Mexicans (as you say) would enjoy the macho connotations of both kinds of Matador.

I have a bottle of "Sweat" in my fridge. The name is not an unintentionally amusing mistake, but precisely an attempt to be amusing. The full name is "Pocari Sweat," and it is not a fizzy drink, but a sports drink with electrolytes, intended quite literally as a replacement for the sweat you lose during exercise.