Factors to Avoid Domain Level Ranking Penalty
Everything is going well with your site. You have been reading about how to rank higher in the search engines and then using that additional traffic to make more money than ever before. Then one day it happens. Your site loses it's rankings for all of it's important keywords. It's disappeared into the abyss of the Internet and you start to panic. You think your run on making money online is over forever.
If this has happened to you don't worry, you probably were too aggressive either with your link building tactics or with your advertising methods. Let's take a look at a few of the top factors that can harm your site at the domain level so you can figure out how to get your site back near the top of the rankings where it belongs.
Getting Hacked
The absolute worst thing that could happen to your site is it gets hacked. Someone breaks into your files and uploads harmful scripts that redirects visitors to another site, tries to scam visitors into giving away their information, or any number of other devious schemes.
It's not always easy to tell when you have been hacked. If Google discovers something wrong you can normally be alerted in Webmaster Tools and your site will be removed from the indexed until the problem is resolved. You can also use Google Chrome's safe browsing to investigate the pages on your site that have been marked as malicious. If you are hacked then you need to make sure to find and fix the problem. Check StopBadware for tips on cleaning and securing your website.
Cloaking
Google's webmaster central describes cloaking as "the practice of presenting different content or URLs to user and search engines." Are you being deceptive in serving different pages to Google than to your visitors? There are not a whole lot of good reasons to do this. The only reason I have ever presented varying content to users was by using geo-targeting (serving different content to different IP locations) and even though that can benefit the user with higher relevance I normally don't even do that.
Selling Links
If you are going to sell links then you need to make sure to include the nollow tag, otherwise you risk getting penalized. I don't sell links on any of my sites, but I have purchased them before. I don't know for certain what the threshold is to lose rankings when a site sells links. A lot of times I still see active cache dates and results in the SERPs when I research sites I can purchase links from, but I do think that if you get caught selling links all of the links on your site lose value and your trust goes down with Google. I recently read a case about someone trying to sell a site on eBay, excessively bragging about how he uses the high PR of that site to inflate the rankings of his other sites. A few days later his site was banned from Google and the worth of his site dropped to next to nothing.
If you are going to sell links, don't be blatantly obvious about it. Having content that advertises the fact that you sell links is going to draw a red flag and make your intent more obvious. If you are selling in-content links without the nofollow tag someone is going to have to contact you directly to see if links are for sale, rather than just seeing it on your site and making an easy conclusion.
Off-Page Factors
Some of the experts think that paid links, comment spam, links from link farms, or other manipulative sources can harm your site. They also believe you are running a risk if you get a lot of links for a short period of time from questionable or lower trust sources or a high percentage of your links use keyword rich anchor text.
I am not quite as sure about this. Google has been pretty clear that they would not allow a competitor to harm someone else's site, and all three of these off-page factors would be easy ways to do just that.
On the other hand, I think Google would interpret these signals as low-quality and discount their value, making your efforts to build links in this fashion go to waste. That's really more of an indirect penalty rather than having a direct, negative effect.
