Back when DS9 was starting, I had heard some things about Brooks. Nothing terribly bad. But something that indicated he had his quirks. I'm sure those shows up on the things he worked on. But his career seems to have flashed. Happens sometimes. He started out in 84. Landed the role of Hawk in Spencer and did that role for all of Spencer and his own spin off as Hawk. Then there is nothing for 4 years. Then he got DS9 and did 4 more Spencer movies and a few other movies. But he really hasn't done anything since 2001. In today's climate I can't see how he could be blacklisted. There are plenty who would hire a good actor and ignore anything like that. I think he had a good income and if he lives wisely, probably doesn't need to work. Plus he is still married to the same woman (celebrated 45 years this year) who seems to have retired herself. I think he is more likely retired than blacklisted and is probably is selective about what jobs he takes. I see nothing in his work history that indicate any issues working with him. He wouldn't have gotten his own spinoff if he was difficult to work with and he wouldn't have such a tight and short body of work. Mostly starring roles as well. I think the data shows that he hasn't needed to work or found a part he couldn't resist. I'm sure for the right part you could temp him. I think the rest is just rumor and hearsay.
