I use a Linux OS (Ubuntu) with Firefox browser. I also have adblock, and the settings are set to block all pop-ups.

I don't think I ever get any pop-ups, or at least if I do there are no notifications. I have ClamTk installed but I don't think it runs in the background (ran a check just now and no threats found).

Given that there's nothing running in the background and I never seem to get any warnings about dodgy sites, how would I know if I was posting a bad link to a site serving malware?