Good topic I too have always been curious about some of these things. But look at it this way. What about web design companies ? Legitimate businesses with a LLC tagged to them or whatnot, multiple high paying clients, SEO companies , whatever, and they would have to use possibly google webmaster tools, or google analytics , as possible weekly and or monthly updates may needed available to their paying clients. I could see a company having hundreds, if not more if you consider google wants the www, the non www, and the http versions all plugged in.
Based on that theory and reasoning if everything is white hat I would think there would not be a problem, I mean if google started dinging and banning all the major companies that use their services, they would go use a competitor, and that is a base they would not want to lose I am sure.
Just my thoughts, but as a business owner, and one who does web design as a side job, all of this has crossed my mind as mind as well, as of course you would keep personal on your personal, and business accounts with your business account, just for organizational purposes and or what not. So yeah multiple accounts, e-mails, multiple sites, I see how it could start to look a little suspect,
Would enjoy some more conversation, theorycrafting on this one if anyone is game.