Yes indeed. I worked with groups of Chinese chemists all on H1Bs. They had to work ridiculous hours and assigned the most mind killing labor. If they made trouble they were told they'd lose their job and it was deportation. Finally the company fired all its non-H1Bs, including me; eventually giving up the pretense and relocating overseas. Where was the department of labor and industry? One of my coworkers contacted them and they wouldn't even return the call. H1Bs are simply licenses for a form of slavery.
Absolutely. You don't have to look far to see h1b sponsors lourding it over their captives heads. Further, if I recall, green card application clock can get reset if you change jobs.. So even if you aren't being abused, you might camp out underpaid at an h1b sponsor till you get that.