These components may negatively affect a spider's ability to crawl a page or its rankings at Google :
1. Server is Often Inaccessible to Bots :
If search engine bots can't crawl your new content then others are at an advantage by being crawled first. Plus if a server is down often search engines may not want to send visitors to that site as much. If the site is not live for more than 48 hours it seems to drop pretty fast from the index.

2. Content Very Similar or Duplicate of Existing Content in the Index :
Since the engines only need one copy of the exact same content, It can affect look ups and/or affecting ranking by biparting inlink value, depending on the nature of the "duplicate".

3. External Links to Low Quality/Spam Sites :
There needs to be more definition on what low quality and spam means. A bad neighborhood is one thing as a low quality MFA site is another. Linking to a MFA site will not harm your ranking but linking to a bad/rough neighborhood definitely could.Linking out to a low quality neighborhood flags you as a resident of the same neighborhood.

4. Duplicate Title/Meta Tags on Many Pages :
Having duplicate titles on many pages severely limits the ranking ability of your pages, especially those in the long tail that will not have many inbound links. Those pages compete on internal links and title tag relevance, so its important to have a unique title on each page

5. Overuse of Targeted Keywords (Stuffing/Spamming):
I think the thing to remember with seo is that when you are developing seo related content and attempting to seo it in the search engines to achieve top seo ranks is that you don't want to overdo the seo to the point that when the page is evaluated the seo comes across and being very obvious, even to someone not in seo. That sentence reads like crap and is overkill - use keywords when and where it makes sense.

6. Participation in Link Schemes or Actively Selling Links :
if the only links you have are from link farms it reflects negatively. Selling links is generally only a problem for hand reviews (manual ban). Done right, can greatly improve a site's rankings. Done overly enough, it can even get a site banned. Depends on how you are doing this. It could not hurt you at all, or it could kill you. Dependent on your method and execution.

7. Very Slow Server Response Times :
Crawlers operate within milliseconds, just be sure your site is able to be crawled as often as needed.A slow server is not a great sign that your site is important.

8. Inbound Links from Spam Sites :
If you have a new site and most or all of your links are from spam sites it might be hard ever earn trust in Google. Older sites with many trusted links can get away with having many more spam links. It is more about the ratio of good links to bad links than the exact number of bad links.