This may seem obvious and incredibly logical to anyone who reads it. But a tip for you all. If you are knowingly spamming Google, do not put all your spammy web sites into the same Google Search Console (Webmaster Tools) account. The folks that issue manual actions clearly are able to see which sites you have linked up in your Search Console account. If they see one spammy site, they may look for others, if they see two or three or four and then see a pattern - that is just asking for it.
Believe it or not, one black hat spammer learned this the hard way. He posted in the Black Hat Forums that for some reason he linked them all together and then within a week or so, a nice percentage of them already were issued manual actions. Don't you know that manual actions are issued through the Google Search Console? Don't you think Google can see this information?
Here is what this webmaster posted, just in case it is removed:
I am sure you know Google collects data from Google WMT. But this is the first time I realized how much they are tracking gwmt. They are literally data mining your info. Ok here is the details of what happened in the last 1 week.
I had about 3-4 sites in the GWMT tools account. I never used Gwmt much but i wanted to play with it about crawl rates,indexing etc. I added like 16 more sites in 1 week.
The first weird thing i saw was "Google" visits. I started seeing awful lot of google visits to the pages i add to the WMT account. The weird thing is the visits are not from bots because Statcounter can tag a bot and also i can see the device etc they are using to visit the site. I see visits from ireland,uk,india,usa google.
After that 3-4 days ago first manual action penalty happened. And today 6/20 got manual action penalty. It is like a virus spreading through the Gwmt account.I am 100% sure when they catch a manual action penalty they are digging deeper to your other sites.
Now the manual actions are pure spam because of spun content from other sites mostly. You can say it is normal right? I used spun content and sites got hit. I added 5 of my other sites that have spun content just like the ones on a new gwmt account. NONE of them has manual actions.All are fine.
Only 4-5 of the sites were important for me. So i don't care much. But i am telling you even if you don't use Black Hat techniques DON'T USE GWMT.
The lesson, if you do use Google Search Console, then make sure to make new accounts - if you are going to spam. Better than that, don't spam. :)
Yes, we covered this topic at least twice before but first time I saw someone post they got caught about it. We covered it back in 2009 and then when Matt Cutts talked about it in 2014. We also covered that many SEOs have access to many web sites, many with penalties and it may not be a concern but it is something you should look at. Meaning, yes, SEOs treat sites that have penalties. They have access to dozens of sites in the Google Search Console. Should you worry about sharing your site with an SEO that has many other penalized sites in their account? Google says no, but really?
Forum discussion at Black Hat Forums.