Why did google penalize most pdf search engines?

I noticed google penalized a lot of pdf search engines (yesterday).

These used to be in the top 20:
pdf-search-engine.com
pdfgeni.com
pdfqueen.com
pdfxp.com
pdflost.com

Now they are all gone. Does anybody have an idea why?

 

same here, today Google penalized most of my best keywords, can anyone explain? how can we fix this? thanks

 

ok, seems google changes them basic arithmetic again, I can smell the next PR update is near

 

Good question. Let me know when you guys find out why they penalized these keywords.

 

Penalized where? On serp or they lost their PR? If majority of pdf sites are being in hit, Google's algo probably had something to do with it..

 

Penalized on serp. All the sites still have their PR.

I also think it has something to do with the algorithm. These sites had hugh traffic because they kept a log (index) of all their searches. The big G must have seen these inner pages as "low value" pages now and deleted them all. They even deleted the index page.

Do you guys think they will reappear in the search engines? Or will this be a permanent ban?

 

not only on search engine position, most of them are literary missing from the search results.
what freaks me out is that, 2 days ago I'm still at the first page for most keywords and #1 for some. but now its gone, as if like I have a brand new site.
FYI (my site is 2 years old)
right now, I have zero traffic from google.com but I still received some low quality keywords from other google domains such as google.it, google.hu etc.

same questions as thepeach. is this a permanent ban? will they reappear if I change the structure of the site?

 

hmm,,, it seems that google has done some changes in their algorithm, otherwise some of these sites were much older and should not be penalized. Since, I am using these sites I have never noticed any blackhat technique used on it to promote it or to get better results.

 

It seems docstoc.com (which publishes pdf documents) is not working as well as it did for me. Before, I would get 200-300 visitors a day to my pdf documents on the site. Now, less than 100.

 

If I search "pdf search engine" at Google, there still 10 results, if someone got penalized, there must be someone's success.

 

I don't know why, I guess because there so many of them now. But several of mine have also been banned regularly in the past few months.
It would be interesting to detect and analyse if some PDF search engines didn't get banned and what difference do they have compared to most others.

 

I do not think this penalization, not sure if we should call it a penalty, are made because of some abused with PDF Spam. I have found many websites using the same PDF file as their contents, which is not a different from duplicate contents issue anyway. I have found many of websites that using a ton of PDF as a content bait, lure Googlebots coming to the town, are not the real owner of them. That was so lame and pretty bad effect toward search results quality in the end.

 

Yesterday, all of my pdf search sites (total 12) was penalized also. Black Friday for me.

 

i guess its temporary fluctuation...

 

Hello, I'm Nejib from France, the owner of pdf-search-engine.com. Google blacklist all of them, (I have an everege of 500 000 unique visitor per day..) only small websites are not blacklisted, I don't think that it's because of Duplicate Content, because my website was the first pdf search engine...but it's blacklisted too...

GOOGLE CHANGE THEIR ALGORITHM... and it's Over for pdf search engine (doc search engine too), they play with us ! no matter, we should be more creative.. other ideas.

 

i am also think its temporary fluctuation..

 

Google wont ban the websites if they promoting methods are legitimate.i think it is normal if they want to update their ranking and i hope they will back normal.

 

I don't believe it will come back to "normal". As Nejib said, we need to move on to other ideas.
But you can still try pdf search engine if you believe it will come back, I don't think so, or not in this form anyway.

 

PDF search engines ??

You mean PDF results in their searches I guess...

 

they web sites are spammer