Came across some advanced search features of twitter in which you can put :) on the end and it will only find searches that it deems are positive.
The whole concept is called sentiment analysis. The attached article breaks down how the idea works really nicely.
If your not looking to do it in Phython here's a few js frameworks;
and the advanced search stuff on twitter can be found here.
If your just looking for pure evil, stick a :( on the end of your twitter searches... or attach this to Google and Google to a awesomo robot and we're all doomed.
Another example is the tweet ‘My house is not great’. The word ‘great’ weights more on the positive side but the word ‘not’ is part of two negative tweets in our training set so the output from the classifier is ‘negative’. Of course, the following tweet: ‘The movie is not bad’ would return ‘negative’ even if it is ‘positive’.