You will need to evaluate a website's content to determine if it is reliable and relevant to your research, but this can be tricky, especially with online sources.
You could apply the C.R.A.A.P. Test as a starting point to asses the credibility of information sources located online:
Remember that it's not exactly a question of "good" or "bad" - it just depends on your purpose. And if you can't use a particular source for some reason, you might be able to use it to find something else - maybe an idea about your topic, or a reference to a scholarly journal article that you could track down.