It's okay to have mixed feelings or a combination of thoughts. However, things start getting a little messy when the feelings begin to conflict one another or when the combination of thoughts is simply irrational. Love and hate or annoyance and admiration for example, two opposing extremes; still we find ourselves loving and hating something or getting annoyed by yet admiring them at the same time.
They say that the people we dislike most are usually the ones that remind us of ourselves, of our flaws. That's not always the case, but it seems to be true quite often. Other times, negative feelings arise from our own insecurities. When such negative feelings are directed toward us, it's okay to be a little sympathetic. It's important to still be ourselves and not let it be an excuse to act like anything less.
And then there are times when find ourselves with extremely positive and extremely negative feelings toward one person all together. I can't help but think even the most extreme negative feelings must stem from some kind of passion. With time, one feeling will most likely overpower the other, but then again, who wants to wait for things to unfold? Especially when you keep finding yourself in the same position weeks, months, or even years later.