Lets use Taylor Swift as an example: If the author States something like "She is awesome" or "She is the best singer". The author is biasing her liking upon the character. But, of course, not ALL people think Taylor swift is awesome or the best singer. If you wanted to see a non-opinionated statement, it would say something like "There are many people that Taylor Swift is the best singer but many others do not". That statement isn't biased. I hope this helps.