I am a current resident at UT-Houston. I'll preface by saying that I ranked the program highly and I am extremely happy here.
In terms of work hours, I work 50-55 hours/week in the main OR and less on subspecialties. Weekday calls are 3 PM to 7 AM in main OR and every subspecialty rotation, usually once per week, and you do not work post-call ever unless optionally moonlighting which is never forced. Weekend day calls are 24 hours but only occur either once (usually) or twice (sometimes) per month.
The clinical complexity is excellent. The patients are incredibly sick, the cases are very complex, and it is the busiest trauma center in the nation. This makes for some very stressful experiences, especially early on as CA-1's are really not shielded from big, sick cases at all on call. It can be overwhelming starting out, but I think I am better for having been put in those situations and having to have made intraoperative medical decisions on my own. There are no M&Ms, only quality conferences where select cases of educational value are presented by an objective presenter.
There are situations in the main OR where residents will relieve AA's at 5 PM. This is a frustrating part of being an integral, necessary part of a large-scale dynamic OR board, but in the context of the overall hours worked I don't think it necessitates a public shaming of the program.
In terms of malignancy, there are 1-2 attendings in the main OR who have a tendency to be blunt with residents. I have never witnessed or heard of a time in an OR where an attending yelled at a resident. I have not personally witnessed any overt abuse of residents by faculty, but I have submitted negative evaluations of faculty. In response to my negative evaluations, the program director addresses the (anonymous) evaluation with the attending and I have seen real, actual change in the relationship of some previously blunt attendings in terms of the way they interact with residents and their overall behavior. The program director is particularly aggressive about fostering and comfortable environment for residents and recuriting faculty who are personable and like to teach.
In terms of residents abusing substances, I've never seen or heard about this but I would encourage the OP to go through the proper channels of reporting this so that the resident can get help before the situation worsens.