These are probably real. It would take too much algorithmic knowledge to fake them. It’s funny how all the examples that get posted on sites like http://www.damnyouautocorrect.com are sexual and/or embarassing.
This phenomenon even has a name, “the Cupertino effect,” a legacy from early spell checkers that tried to replace the (unhypenated) word “cooperation” with “Cupertino.” (or maybe it was a plot by Apple?)
Now spell checkers are context aware. They use Bayesian algorithms and trillion word databases, as explained in
And of course they can be “trained” e.g. by “add word to dictionary.” One might be able to learn a lot about some people from their Custom Dictionary files, which aren’t hard to find.
Hmm, I wonder if “Gay Guy Friend” (in the second example above) actually added “assplowing” to his dictionary for convenience. Maybe he just used it a lot.