Question

Why is it important to determine if a site is biased?

Answer 1

It is important to determine if a site is biased because this means that you are not obtaining the right information. If a site is biased, then you can only hear one side of the information. You will not be able to obtain the information you need thus, you probably will get a wrong information. 

Answer 2

Let's say that a reporter is supposed to report a home domestic violence case.

If the reporter grew up in a abusive home, chances are the reporter will be quicker to assume that the suspect is indeed a violent person person who is attacking people in his or her home.

If the reporter was wrongly accused of such a thing, for example, it might change drastically the way he views this matter. In this case, the reporter will most likely calmly approach the situation and look for evidence instead of quickly presenting someone as guilty.

This show how bias can already change the tone and message of something being reported, making it be perceived in widely different ways.

It is very important, then, for you to know who is behind the information that is being passed to you and their connections. A channel called "Russia Today" might very well be more complacent about Russia's deeds. A conservative channel such as Fox News might very much defend conservative points of view even when they're highly debatable. Same when it comes to liberal points of view and most News Channels.  It is also very important for you to check past articles about the same sort of subject to see how this or that source behaves when talking about the same sort of topic and compare to others and how they behave. And this can be used for TV Channels, Blogs and other sites, magazines and so on.

it is very important for you to check if your source is biased because you might not be receiving the whole story from that source. Sometimes, you might not even be receiving a partial true. We are in the age of information and with it, comes a lot of disinformation as well.