It can happen to the very best of sites managed with white hat SEO as in this case study found on the MOZ blog; Google smacks your organic placement down and you can’t even find your business name in a search on Google.com.
Usually this type of severe penalty is reported to you on the Google Webmaster Control Panel under manual penalty.
John Mueller of Google responded to the MOZ blog writer’s question on negative SEO tactics with this response:
“…You mean like when somebody creates spam links but also links to Wikipedia? … We have seen it happen before. Sometimes we can tell but sometimes it’s a little bit harder… but [if] you get a manual penalty from it you will know about it so you can just disavow the links.”
Other SEO have stated that to remove a Google penalty you should work to manually clean up links before using the disavow link tool, but clearly Google feels otherwise.
If you have not been using shady or spammy link growth tactics and you’ve gotten a Google smackdown, make sure you review your link numbers in the Google Webmaster Control Panel and disavow those that you have not worked to grow. It may be the fastest way to get your position back.