Biased information is dangerous because it is not an objective opinion, most of the time it is based on personal accounts or experiences, opinion, prejudice, misconceptions, fake news; The internet is full of biased information: people look out for facts at the same sources, provided by search engines, then end up developing the same conclusion on a subject because it fits a pattern that appears as adequate.
When researching, think of the connotations of what is written; if it reflects an inclination; if it is based on proofs; what information is it lacking (does it provide a complete view on the topic?). Going through biased information is a very common issue on the internet, this is why is important to identify them.