I disagree on Digg. I didn't mind the ads. Not enough to stop using the site, anyway. What I minded was the transition of the content to advertising. Plus, at the same time they did a site redesign that made it look like one of those auto-generated news sites.

Comments on youtube... yeah, they're crap for most videos. I guess technically comments are user generated content, but I never really think of them that way. Even more so on a site like youtube where the videos are the important bit.