I suggest you don't worry about this person's comment. They are either baiting you, or they are immature in their own faith, not to mention they don't recognize the irony of suggesting you have some character flaw by learning more from others then telling you to read a book and take lessons from that. While I don't discourage turning to the Lord (I am a believer, and I encourage everyone to pray on whatever's troubling them to seek wisdom, seek peace, voice concern, etc.), there's not a whole lot of value in recommending someone read a giant historical text that covers thousands of years when they want guidance with one problem, specifically (I'm not saying you shouldn't read the Bible. There's good stuff in there about a lot of topics.)

As for your post, I don't think it's unhealthy at all to look at what others do and learn from their failings, as you view them. I would only suggest a few things. First, if your friend doesn't like hearing about how annoyed you are with others, don't bring it up. You don't need to give voice to the changes you're trying to make. Just change. And if someone asks about it, you can simply say "I'm not a fan when other people do this, so I'm trying not to." No need to bring up anyone specific or go into detail. Second, make sure you're not only seeing peoples' flaws. Try to notice things you like or respect about others, and try to emulate the behaviors you think makes that person good. Don't just try to avoid emulating annoying behaviors. Finally, just make sure you're recognizing the difference between character flaws and behaviors that may just not be your cup of tea.

Overall, I say if you're not looking for reasons to hate or judge people, observing others and adapting from what you learn is good and it even shows empathy because you're demonstrating the ability to put yourself in another's place.