Most roommate situations don't involve everyone baking cookies together, sitting down every night to eat dinner together, or constantly hanging out in the living room despite what every sitcom wants us to believe. Usually, people sharing a living space barely see each other and when they do, it's to have a standoff over who takes the trash out more and why one of them never does their dishes properly. Everyone has their own standards for cleaning, clutter, appropriate sound levels, guest policies, or pets, and it's important to make sure everyone is on the same page before signing a lease with someone.
Of course, some roommates can become your incredibly close friends and there are definitely people who are able to cohabitate without a problem for many years. Still, it's always good to be extra prepared. It's not always the most pleasant surprise to find out the person you just dropped first, last and security for is a tap dancing nocturnal kitten breeder/paper cup hoarder.