If it's funny, intentionally or otherwise, I'll hit it. Even when there was an "unhelpful" button, I seldom pushed it. If someone had a differing point of view, but presented their "evidence" and opinions in a semi-plausible way that didn't sound as if they were coming straight from the Republican playbook, I'd mark them as "helpful". Sometimes, of course, those with a differing opinion from mine differ in such an extreme and flamboyant fashion that I can't help but laugh, and hit the button.