Great question......any numbers of things will grab my interest enough to want to read a hub. However, I would have to say, the "Title" as well as first couple of sentences......sometimes, even a picture or graphic will pull me in.
I assume you're referring to hubs written by hubbers we don't religiously follow. I read most all of their hubs, unless they're "recipes."
On the other hand, as long as we're giving opinions......there isn't much of anything that can entice me to read any kind of religious rant......I'd sooner stick needles in my eyes..