Coworker goes through colleague's phone and finds texts calling her annoying, starts spreading rumors about her in the office: 'I never leave my phone out in the open, so that means she had to go through my stuff to get it.'

If she can prove that she actually read her texts, she could get herself fired. 

One of my biggest fears is someone hacking into my phone and reading all of my nefarious texts. It's not like I'm confessing to anything that will put me behind bars in my texts, but I have definitely said things that I wouldn't say in mixed company. The price of community is annoyance. Let's just say I've got a pretty large community around me, and I can't love everyone in it. It's crucial to get negative feelings out of my system, and ranting to my friends is my preferred way to do it. Who among us doesn't have those friends with whom we text every little thought, no matter how dastardly? We all have a right to privacy, and sometimes expressing your frustration to someone else is the one thing keeping you from taking it out on the person you're frustrated with. 

I can admit that I have negative feelings towards some people, even if they haven't technically done anything wrong. It doesn't make you a horrible person if you don't like someone, but you shouldn't be openly cruel to them if they have never wronged you. I know better than anybody that it's not always easy to pretend like you like somebody when you don't, especially when they can see on your face that you don't really care for them. 99% of the time, it's best not to tell them directly that you don't like them. After all, would you really appreciate your coworker telling you they don't like you when you could already tell?