Giampy, I wouldn't call those pop-up/pop-under advertisements hijacks, and they're not necessarily full of malware - the products they advertise are definitely snake-oil, though.
But if you visit sites of that... quality... where they use advertisements that are allowed to use those tactics? You really, really, really shouldn't be browsing without NoScript + AdBlockPlus. Heck, people who frequent that kind of warez/pr0n/stream-tv-shows sites should be doing so from a browser not just with NS+ABP, but preferably a sandboxed one, and it definitely wouldn't hurt running it from a VM.
Paranoia? Only slightly. Even if the sites themselves aren't sleazy enough to serve you malware, their banner advertisement affiliates might be - and even if they aren't, they're nice goals for hackers to inject malware into.