What if you had a reason to snoop? What if you had a gut instinct that pushed you to snooping. I think if you snoop and you find something that the other person is hiding then the snooping was justified. If you thought your partner was hiding something from you (like another person) and asking them wouldnt get you a truthful response would you snoop?
Snooping is bad, but I think if your partner has given you a reason to be suspicious, then it's primarily their fault for not being open and honest. Of course if you snoop, and don't find anything, then it's primarily your fault for being insecure.
I had a boyfriend who was always suspicious of me, which he admitted his trust issues came from the fact that he'd cheated on several girlfriends in the past and knew how easy it was to hide something from someone, so I was always suspicious of him. So, once I did snoop, I found a lot that he had been hiding from me. If your boyfriend doesn't have a history of cheating, and hasn't given you any reason to be suspicious, then snooping would be bad. If that's the case, then you should really examine your own feelings, is this an insecurity? Is it paranoia? What have you experienced that might make you feel suspicious of someone who hasn't given you reason to doubt them.
No, If your partner has never done anything to earn your distrust, than it is unfair for you to snoop on him. Snooping crosses a line in a relationship - being constantly asked if he is cheating or feeling like he is constantly being spied on is going to drive him away. A partner should not feel like they have to prove themselves constantly.If you feel you cannot trust him, and you do not trust his answers, then maybe the relationship is not for you, but also, consider whether your gut feeling is actually your own insecurities emerging.
Part of love is trust. If you can't trust your partner then you should not be with them. Why be with someone who you're always suspicious of? That's not a healthy relationship. If you are concerned, speak with your partner about your concerns. Otherwise if they are being secretive, may be time to call it quits. Don't forget that there is a difference between being sneaky and wanting privacy.
Gut instinct is not a good enough reason. If you feel that strongly about it, TALK to that person, otherwise you're betraying them for possibly no reason. If you can't even trust the response of someone you care for, it's not a good relationship! Communication is the only way people stay together, so your snooping just shows you didn't want the relationship anyway, whether the person is doing something wrong or not.