The valid inference about what was known about Bellevue's reputation from the excerpt is:
Bellevue's mistreatment of patients was known at the time.
This can be inferred from the description of the ferry boat filled with "unwashed and uncomprehending women" and the ambulance driver's warning that it was "an insane place" where "you'll never get out of." This suggests a negative perception of Bellevue and its treatment of patients.