Finally, there's "goodnight". This topic is reaches trending topics almost every day, simply because somewhere around the world, people are always going to sleep. But is it useful? It's debatable. It is a legitimate topic and therefore there's nothing wrong with it trending, but since it's always there, one could argue that it's taking the place of other, perhaps more interesting topics. Twitter should seriously consider permanently banning certain words from the topics; but it opens a Pandora's box of possibilities; what if a movie called "Goodnight" comes out, and thus this topic suddenly becomes legit again?
Twitter is becoming very big very fast, which is every company's dream come true, but it can also bring a lot of problems to the promising startup. Trending topics are becoming a very important part of the Twitter experience, and Twitter needs to find a way to deal with spam and fake accounts.