When staying in a dorm with a dozen other people, the first rules of common decency are be quiet and keep it dark. During a recent stay in Šibenik, Croatia, I had the good fortune to stay with a British chap who after a night out, turned the lights on at 2am so he could read his book. What a guy.
The Spiritually Awakened Chatterbox
Whether they've just done ayahuasca, or discovered some deeper meaning of life, you will always come to find someone who will want to share their amazing realization with you.
No matter how many people you ask, Australians often come up. "I've met some particularly shit Australians during an ill-advised stay in a hostel," a fellow music journalist told me when asked. (Note: Brits and Canadians just barely escaped their own categories.)
The Kid Who Never Leaves the Hostel
Traveling in South America you often bump into the type of unfortunate introvert who watches films in the common room all day, and drinks all night in the bar. (For those who've been to the Flying Dog hostels, you'll know exactly the type.) Get out into the world already -- it's right outside.