Just last week while playing online I was signed out of my account and a message popped up saying "Disconnected because account was signed onto another console" I then quickly signed back onto my account and another message came up saying "xThree DoGz (my gamertag) was last signed onto another console" Of course I thought someone tried to hack into my profile, so I changed my password. Not even 10 minutes later the same thing happened again. This time when I changed my password I called Xbox support for some help. After about 30 minutes of being on the phone, my friend that also plays xbox texted me saying that his friend accidentally signed into my account (I had recovered my profile on that console a while back, but I had it back on my xbox for a few months now) That was why it signed me out, but when his friend signed onto my profile he didn't have to enter any emails or passwords, he didn't even have to download/recover the account. It just signed him right on.
Then just a few minutes ago I needed to sign in a guest, but it wouldn't let so i signed onto my friends profile (The same friend who's console I had my account signed onto) When I chose his profile it signed me right in without passwords or needing to download it. I was able to play on it like he had actually recovered it.
This needs to be fixed ASAP, most people don't think about deleting their profiles from other consoles because once they recover it back on their own xbox, they know that if someone wanted to sign onto it from another xbox they would need his email and password.