译文：
1.先寻找你网络流量进行分析下降和垃圾流量趋势.
2.查询[site:yoursite.com]搜索google,看google对你站点URLs链接索引情况.[这里应该是相同标题等问题的URLs]
3.Google Webmaster Tools的报告看一下.
4.Google PR是否改变了(Graybar-- NND找不到这个词的解释貌似是一家公司.)PR可能是一种惩罚信号
5.输入你的网址进行搜索(格式不带www和带www种不同的顶级域名).如果查询-50，可以肯定google的一次惩罚了.:)
6.检查是否已列入黑名单，因为谷歌浏览你的网站不安全(这个应该就是那个提示病毒啊什么的那个,在google网站工具箱看).还有这个直接查询的http://www.google.com/safebrowsing/diagnostic?site=mysite.com --给出你的域名.
7.检查你的源代码,看看是否被加入了黑链.
8.检查一下站点 WHOIS资料是不是同一个人,还有站点统计是不是和另外站点同一个统计名称.
9.从你网站某页或者主页关键词截取长词组,去google精确匹配的检索,确保第一页一个结果是你的(状况没有出现主页,没有出现其他站点内页)
10.检查你的URL是否出现结果为0，或者在结果数里出现show omitted results(结果显示省略)链接.(这意味着你被认定了重复）
--感谢记忆哥的英文功力。
原文：
1.Dig your internal traffic analytics for traffic drops or bad trends;
2.Perform [site:yoursite.com] search in Google to see if Google reports same number of indexed URLs;
3.Check if Google Webmaster Tools report any problems;
4.Take a look if Google toolbar PR has changed (graybar PR might be a signal of penalty);
5.Check your site ranking for a “domain-name” search (without the TLD).If such a query puts you in the fifties, it’s almost (!) guaranteed to be a penalty.
6.Check if Google has blacklisted your site as unsafe for browsing (type http://www.google.com/safebrowsing/diagnostic?site=mysite.com with your domain at the end).
7.Check the source code for any injected links to obvious “bad neighborhood” sites;
8.Check your other sites. In some cases Google seems to devalue the WHOIS domain owner and this results in a simultaneous ranking drop in several sites under the same domain account.
9.Copy a long phrase from your page and search Google for the exact match – make sure this very page (not the home page, not other sites scraping yours) is ranked #1;
10.Check if your URL can only be seen by adding &filter=0 to the search URL – or clicking on the “show omitted results” link (this means you were hit by the duplicate content penalty);