Google verify the sites whether operated by webmaster or website owners, when their sites required a manual action.
Recently Marie Haynes posted on Twitter regarding the spammy clients, to get the help from Google’s head spam Matt Cutts. He twits on her comment, all about the spammy links are having her site along with other properties of the site.
Matt Cutts said that, if you get the manual action of your site before you need to consider that Google may have noticed about the spammy sites.
But you need to be aware of the facts that Google may not always take the review of the other sites operated by webmaster. If they do as then it would be massive consequences across those properties.
Below you can see the twits of Matt Cutts
If Google aware of several
It seems like bad review for a webmaster