In other words, you don't trust the people you trust. Perhaps you need to rethink your behavior, based on your revelation that you don't actually trust them.
Some of us have had significant others with jealousy issues. It's not that we don't trust them, it's just better if they don't worry about silly issues like whose Facebook profiles we've been perusing. Not because it's a secret or because there is anything to hide, just because it helps the SO control their counter-productive impulses if they aren't informed on the matter.
That same kind of avoidance can be applicable in all other sorts of relationships. It's not that the people aren't trusted, it's just that there's no reason to know, and it will only cause damage if they find out -- not because it's bad or trust-breaking, but because the person's reaction may be problematic for completely different reasons (compulsions, or potential taint of future circumstance).
It just doesn't make sense to insist that both (a) I want to leave everything unlocked and open; and (b) I don't want anyone to be able to see what's there.
You've got every right to protect your privacy from prying eyes. But if you want to do so, do it.
I normally don't bother logging out of whatever sites I'm logged in to.
I'm not too bothered what she sees if she opens up the Facebook tab with me logged in - but I can see that it may be a problem for some.
And I don't think that "hand it over for five minutes to check something" is that uncommon a use-case.
I'm not too bothered what she sees if she opens up the Facebook tab with me logged in - but I can see that it may be a problem for some."
That's the crux of it - you're not bothered by it. If you were bothered, surely you'd hit the 'log out' button?
"here - look at this interesting article on Wikipedia" ... she starts reading ... ... I get bored and go to make cup of tea, forgetting that I hadn't logged out of Facebook ... ... she finishes article, closes tab and finds herself on my Facebook page ...
It is my fault, but a "clear history" (or at least make my history invisible) function would mean that mistakes like the above will have much less impact
Facebook doesn't show which profiles you've viewed explicitly for a good reason - I think they were just hoping that this would be obfuscated enough not to get much notice.