This is how people have viewed 4chan for a while now.

People think anyone who spent any time on 4chan are pedophiles/racists/misogynists.

They're mainly right but it's a mixed bag.

Don't get me wrong 4chan can be a horrible place but most people just assume if you visit 4chan you're on /b/ or /pol/ which is generally where things can get really dark really fast.

4chan does have some decent boards though just that you always have to be on guard for trolls.