Remember that the words you enter in a burst of passion or indignant anger will be there for you and everyone else to see (even in search engines), sometimes long after those intense feelings have passed. That's not meant to discourage spontaneity, but just a friendly reminder of the long-term existence and effects of what you post.
You may, from time to time, find yourself in disagreement with someone else's opinion. At times like these, please keep in mind it's safer and more polite to take issue with the comments rather than the person.