How often do you read it? I recently moved to the DC area so the Post is my daily paper, and while I wouldn't read it if wasn't reputable, I don't think anybody can call it unbiased. It's not just the presidential campaign, they have clear, almost plainly stated bias in lots of areas. I'm fine with that, because it's not hidden and it's not so egregious that they report false stories or something, but the Post should not be your only source of news.
Are you joking? The Washington Post is one of the most left-leaning, biased papers in the country. They're not even subtle about it. Do you honestly not recognize this?