tedster - 9:48 pm on Dec 14, 2012 (gmt 0)

I'd say one minor spam signal could be pages that have very similar content overall, but that target slightly different query phrases. This is actually something like the old "blue line" pages that some SEO software from the 90s created to be used as doorway pages.

Depending on how many pages are involved, this could even be promoted to a "major" spam signal and get a severe penalty. When it's just a couple, it's minor and all but one page gets thrown out of the index.