enigma1 - 9:32 am on Apr 16, 2012 (gmt 0)

A 301 redirect of a page that has never actually existed to a 404 page isn't a problem

If the bot sees it, it may create a soft error in GWT. Do a valid redirect to a valid page, or a 4x right away.

they are using non-hyper-texted URLs to find new content and it sometimes causes 404 in WMT.

I've replaced the 404s years ago with redirects so I don't get any errors even if the bot finds something that looks like a link. Looks like infinite 404 error space may hurt after all.