Not in the habit of staying logged in on anything I'm not using.
Do you keep your browser history etc. too?

It isn't that SIGforum has a particular risk to staying logged in, it's just not a good habit to start.

When I visit the site using a lap top it automatically logs me in.

When I visit the site using my smart phone it doesn't automatically log me in. Hence I can check out what is new but must log in if I want to post anything. So if I don't post anything I must be showing up as a "guest".

Perhaps that is the case with other members and their smart phones?