Two possible corrections: "we cannot *always* trust what we read on the internet" OR "we can only *sometimes* trust what we read on the internet."

It's wrong to believe *everything* the internet says, AND it's wrong to believe *nothing* the internet says.

It's right to read the internet with a critical eye. I read this piece critically enough to see that you understand the truth, but twisted it in your summary (above). An uncritical reader might have only picked up on your summary and been misled.

There are several signs of relatively trustable and relatively untrustable texts. One sign is how much care a writer takes in making his/her points.