The valid inference about what was known about Bellevue's reputation is:
Bellevue's mistreatment of patients was known at the time.
This inference is supported by the excerpt, as the description of the ferry boat filled with "unwashed and uncomprehending women" and the comment by the ambulance driver indicating that it was "an insane place" where one would "never get out" suggest a negative view of Bellevue's treatment of patients.