I have discovered something interesting

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Brenda Michelin: Errors on their end, I might guess? Very thin content? Duplicate content?
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  Allan Khazak: Do you think they are doing this for a link boosting standpoint? The content is very thin, does it provide extra value from SEO standpoint?
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  E Dieter Martin: Are they advertising on Google and use those pages as landing pages?
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  Allan Khazak: E Dieter Martin No they aren`t, when I check ahrefs these pages are ranking, the city pages, not service specific pages for each city
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  Brenda Michelin: Allan Khazak so, which pages are they noindexing? the service-city pages? or the location pages?
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  Allan Khazak: Brenda Michelin service city pages
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  Richard Hearne: Non-indexable in Screaming Frog can to caused by:
  * different canonical URL
  * Robots META NOINDEX
  * HTTP NOINDEX Header
  * non-200 response code
  It sounds like perhaps these pages are intentionally set to NOINDEX. Google does not like doorway pages like this. Historically also referred to as "Cookie Cutter" pages.
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  Allan Khazak: Cool thanks, but does this benefit their SEO? And if so, how?
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  Richard Hearne: Unlikely to benefit, but it might perhaps have lifted a previous penalty or algorithmic dampening of their site. This type of content scheme resulted in lots of penalties for sites in the past, and is generally frowned upon these days. I wouldn`t take too much educational inspiration from a site that uses this content pattern.
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  Allan Khazak: Richard Hearne great thanks for the details