I worked on a couple smosh series. Smosh doesn't disable its youtube comments, probably because they get a big chunk of change from Youtube. Even accounting for the fact that it's Smosh, the comments lowered your IQ just by looking at them.
Much like standing in line at a grocery store and your eyes being caught by magazines like Cosmopolitan or People. I can physically feel my brain cells dying the longer I stare, and try my hardest to look at anything but the colorful, designed to catch your eye magazines. I worry the day will come when I can't stop staring, and I'll turn into an inert, brain dead mass right there under the fluorescent lighting.
I deleted an IQ lowering joke and replaced it with the current last sentence. YouTube comments probably aren't even the worst on the internet. Ugh...