[sic]

This is one of the prissiest things you can do today. In the past, when nobody made any typographical errors it might have been permissible, just due to the sheer transgressiveness of any misspelling. Nowadays everyone misspells. With blogging becoming a thing respectable professionals do (why did they ever put themselves in a class with cranks like me, that was the first mistake) even respectable people make mistakes now.

Putting "sic" after people's errors is a nasty thing to do. It says "I noticed the mistake this person made. I am a better person than him. I think he is scum." There are at least two better alternatives:

• Correct the error yourself, without calling attention to the fact that you did it. If someone has written "serendipitouss", it is usually pretty clear what he means. And unless he is the world's worst person, he won't object to your "misquotation" of him. Unless someone is really looking hard, they won't even notice that you've done it. They will only notice a perfectly written article, with no jarring "sic"s.
• Leave the error intact, without a "sic". This might make people think you are a misspeller. But as I say, that is becoming a less and less shameful thing to be. And in any case, you know you're innocent and that's what counts. This also has the advantage of honoring the original writer's intention, just in case he actually did mean to say "serendipitouss".