Hate to disagree with you lil_buddy (I usually don't!)...
I think snooping is absolutely toxic to any relationship (including looking in medicine cabinets of friends, etc.)
If you snoop and find something hurtful or secret - you're either stuck with that knowledge or you have to come out with it, proving you're a snoop... so either way - game over. It destroys trust. Period.
If I don't trust someone, I keep my distance. If I'm concerned about my partner - I ask openly. I found out my ex was an obsessive cheater because he left evidence in plain sight. Multiple times. Denied everything.
I have lived with my current housemate for years - I have never looked at his phone, computer (I look away from computer screens unless invited by the person using it to see something), opened any of his office or bedroom drawers...
I believe in simple respect for privacy and manners. And I expect the same back.
I read a post earlier/yesterday in which someone commented that "all women snoop" and that really got me a little frosted.
It is so unhealthy and so disrespectful of the person being snooped on.
When it comes to kids - I made it clear that if they ever gave me a valid reason to snoop on them - in any manner I chose, then I would - and it would be a consequence of their behaviour, thus my concern for their safety or health or whatever. Sometimes their honesty has been unexpectedly difficult, but far better than the alternative.
That's my view, anyway... I know lots of people disagree with me - that's fine as long as they don't snoop on anyone in my world.