How do you know if you have been penalized by search engines?

[StreetwiseReports]

How do you know if you have been penalized by search engines?

I logged into my Google and Bing webmaster accounts and all looks ok, but in the last 30 days, my organic traffic has decreased 33%. My traffic usually steadily increases and if there is ever a decrease, it's usually very small.

[AlanBleiweiss]

Penalties can happen for a lot of reasons these days.  One of the quickest ways is to see if you can associate a specific, clear drop in organic site visits with a known date of one of Google's many publicized updates.  (either a drop on an exact same day as an update or within a day or two after).

Examples of clearly identifiable drops related to specific Google updates can be seen here:

http://twitpic.com/9bfx2s

http://twitpic.com/8pjere

http://searchmarketingwisdom.com/wp-content/uploads/GoogleSurvivorTipsSlide3.png

You can compare your own analytics with the known dates tracked here on SEOmoz

However if your site was penalized due to a "cascading" effect, that could be more difficult to pin down.  For example, if your site suffers from a combination of "red flag" issues, it could be that you were on the verge of penalization for quite some time, and only an accumulation experience triggered it.  (the last straw to break the rankings).

Another consideration is if you have seen a big drop recently, you could very well bounce back in short order if it was just an accumulation of "perfect storm" factors (including changes Google made that they then shortly thereafter "fix", for example).