Yes – crediting the source is polite. I make a point of linking back and crediting, and expect the same those of you that find what I write interesting. That said, spammers are inherently rude. They don’t change their ways when asked politely.
If a publisher doesn’t want their publication re-published (w/ or w/o credit – the come together) then they shouldn’t be using RSS.
Or the internet.
Or anything that can be digitized and uploaded.
Or the publisher could put a block on any site they don’t want accessing their site, something in the .htaccess usually works pretty well.
Fun for the Comments: Re-state the quote above without using the blacklisted buzzwords.