Like everyone else, I, too, always assumed that it was because either they were idiots or non-native English speakers. But I have very recently learned that is not the case. Indeed, the real answer is one of the more astonishing (at least to me) things I've heard in quite some time!
It turns out that the dead giveaways of "spamese" are completely deliberate and carefully calibrated. Huh? Why? Because very few people of the type who frequent Quora would be fooled for ten seconds by these things. And guess what? Quora readers are the ANTI-audience for them!
Instead, the obvious giveaways are used as a *pre-qualifier*, to ensure with the least possible effort that the ONLY people who respond to the scammers' initial mass mailings (and therefore have to be brought along individually during the later stages) are the absolutely most gullible, ignorant, susceptible, suckers they can find.
Absolutely brilliant!
UPDATE: Microsoft has published a detailed research paper explaining this, which was helpfully pointed out by Ariel Krakowski and Jared Fleitman. The full text of paper is available at
http://research.microsoft.com/pu
