This post is an etiquette post that mentions resteeming but it's the only one I've seen that addresses the resteeming issue. It kind of talks more about how it is or isn't to your advantage to resteem rather than whether it is polite, which may be why other etiquette posts don't include it.
I did a bunch of research before and just after I started steemit. The 'guide to success' posts don't generally mention resteeming either.
Thanks much! What a great resource. It's true - there doesn't seem to be a lot on there about resteeming. Just checked out your blog, and hit follow. Living off the grid has been my dream for so long! Super psyched to start reading up on your adventures.
I look forward to seeing you there!