Selected answers from the Dumb SEO Questions G+ community.
Justin Y: I don't think it has anything to do with a penalty. Did you receive any notices in your Google Webmasters Acc? <br />Too help speed up the re-indexing process you can post the links via social, ping the site, and or resubmit your XML Sitemap in WMT.
Lori Eldridge: Google usually doesn't come back very often unless you update your site frequently. google only provides notices for manual penalties. If a site is hit by an algorithm or Panda/Penguin penalty there will be no notice.
Lewis Barrs: The sites are updated constantly, socially active, havr been pinged, site map submitted. Obviously not manual penalty or I would not be asking. The question is, the website will not get cached if it is in some type of algorithmic pe alty/sandbox. Also would like to know your thoughts on this, <br />Domain hit with some form of algo penalty, is it in this sandbox for a set time or will it regain organic positions as soon as say a bad link is removed?
Justin Y: huh? <br />Google doesn't come back unless you make changes to the site? <br />How does Google know you've made changes to a page if they haven't even crawled it?
Lewis Barrs: That is the point, no changes will be picked up until it is crawled, the question is why is it taking a ridiculously long time for them to crawl it? ;As stated earlier the sites in question normally get crawled a whole lot faster than what they are now, so why has this suddenly slowed right down
Justin Y: I'm not sure how savvy you are with everything, but have you checked your robot.txt file to make sure the site or directories aren't being blocked? <br /><br />Have checked in Google webmaster tools to see if there are any crawl errors?<br /><br />Also I think it can take longer at times if your pages in question are buried deep into the site.
Lewis Barrs: No crawl errors, the domain as a whole has slowed right down as regards to cache, i.e home page. I am thinking that the crawl process slows down to your domain if it is in some form of penalty, keeping you down regardless of what you are doing on the site.
Lori Eldridge: @Lewis, The only way to tell if you've been penalized is to compare your site traffic to the updates of Google's Algorithms or Panda/Penguin Updates. Several sites keep a record of these but searchengineland is a good one. If your traffic hasn't dropped then it could be (if your site is new) that Google has removed the boost it gives to new sites. It could also be that Google is preparing for a new update of some kind and not indexing pages currently. ;