One thing to consider is the possibility of retaliation from the evicted roommate. You may well be within your rights to evict that person from your residence, but that doesn't guarantee your personal safety after you do it. He or she may decide to harass or otherwise intimidate potential new roommates, for example. Flyers and posters announcing the need for a new roommate could be vandalized or removed. There could also be harassing phone calls or letters to deal with if the former roommate has difficulty moving on with his or her life after the eviction. A temporary restraining order (TRO) may become a necessity if the former roommate becomes intrusive.
I was in a situation one time where an ex-roommate had just been evicted before I met with the other roommate who placed the ad. He was a bit of an oddball, but nice enough as a potential roommate. I moved into the apartment, got my keys and set up shop. A day later, the phone rang and I knew it was for my roommate, since I didn't even know the number at the time.
On the other end was his former roommate, and he realized I wasn't the person he was looking for. I must be the new roommate. I didn't know the whole story about the eviction, but the former roommate starting getting very agitated while talking to me. He demanded to know where "Dan" was, and why he was already allowing someone else to move in. Apparently, they had gotten into what sounded like a lovers' spat, and now he had time to cool off and talk to "Dan" about their situation. I had no idea the eviction was this complicated or emotional. I am not homosexual, and I didn't really care to know the sexual orientation of my roommate. That was his private business. But I found myself in the middle of a very tricky situation because the former roommates weren't clearly at peace with the eviction.
The other thing I learned is that it is very important for a new roommate to introduce themselves to the manager of the apartment complex or the landlord of the house. If you are not on the lease, they may not be too anxious to open your shared apartment door if you lose your key or your roommate cannot be reached for verification. Conversely, a tenant should inform the landlord or manager if he or she has asked another roommate to leave the premises permanently. Discovering an unknown face in a tenant's apartment can lead to some serious misunderstandings down the road.