they all seem like pit mixes

It is a pit bull rescue site. There are many homeless pit bulls. Generally pit bulls and mixes from pit bull rescue societies are temperament tested and they will honestly tell you if the dogs are dog aggressive(not a good choice for the inexperienced), good with cats or not and good with kids. Check out this information for any dog you adopt, some shelters are more responsible than others. Some shelters spay/neuter any dog that they adopt out...others don't. Some do home checks others don't. PBRC is a reputable organization that isn't trying to "dump" inferior animals, but a reputable organization that wants to find good animals good homes
Keep an open mind and do not judge all pit bulls from the hysterical stories you see daily in the media. I have owned several pit bulls and enjoyed them all. Not one of the pit bulls I owned ever exhibited and aggression towards humans. A couple did not get along with other dogs, however. Then the best dog I ever owned (a pit bull from the dog pound) loved people, kitty cats and other dogs and children.
All dogs have teeth and can bite. I have owned other breeds too besides pit bulls. Some were good with other dogs and cats and kids and some weren't....
If you don't feel comfortable about the breed, don't adopt one. There are many loving homeless dogs of all breeds available. Did you know that black dogs don't get adopted very often? This is a phenomenon often observed by shelter workers. As this tribe is black dog lovers, you should know that there is no reason for this. Black dogs are just as loving as any other color, just as smart, just as trainable. Some have faults and some are perfect angels.
Thanks for the venting space...