I have multiple g-mail accounts. One of them is my primary personal one, and another one I use is a shared account that my band uses for business and soundcloud.
Google makes it hellish to sign out of one and into the other. For the longest time, I had them linked, and my band mates could see my personal e-mail. I don't know if they could get past a log in point, but the fact that its so hard to keep them un-linked and log into one or the other is infuriating.