Not so much rant as 'wtf? where was your editor?'
There's a certain kind of fanfiction in which I do not expect to find a mistake such as the one I saw today (an "it's" that should have been an "its")
In the published book I'm reading on the bus to work!
Specifically a Torchwood book called Skypoint that refers to the events of Gwen's wedding day, describing the alien baby and "...it's shapeshifter mother..."
It's small and nitpicky but it really threw me out of the story, more than it would have if it was something I was reading online because this book (presumably) had to get past at least one editor!
I also find it both awesome and failtastic that I've read online fanfiction with better characterisation that the published Torchwood books I've read recently. Admittedly only three of them but those three have not inspired me to want to get more.
Edit: finished the book while eating lunch and (of course) the first line in the acknowledgements turns out to be "A writer's greatest friend should always be his editor."
I had to laugh.