For a person, like me, traveling alone, meals in the dining car are a total crapshoot. But if you accept that, all will be fine in the end, epsecially on a multi day trip. I've been seated next to someone who insisted on telling everyone bout flying saucers -- the off button didn't exist, or at leat I couldn't find it. I explained to the crew that this guy was a little over the edge, and they were careful to spread him across the rest of the pax. Everybody got to enjoy one sitting with him, but not two. I've also been seated (on the Cardinal) opposite to two senior ladies with no teeth, who just talked to each other for the whole meal. Again, the crew was careful to give me a different perspective on life at the next meal
At the other extreme, on the Cap Lim it was just me and a lovely older lady whose husband worked his whole life for PRR management. Amazing stories.
My favorites are when 2 or even 4 tables all start talking with each other, especially if folks are swapping rr war stories.
The bigegst problem for me is when someone aggressively pushes polltics (or especially non-fact-based opinions) that I disagree with. If you want to take the person on and try ro educate him/her. more power to you. But don't be shy about leaving the table early and heading back to your sleeper. People have always seemed quite willing to stand up and let me get by them.
Good luck and good cheer.