The term "Rusty Darvish" sounds like a hygiene-related illness common among prospectors and mountain men of the late 1880s.
"Did you hear that Ol' Frackles caught the Rusty Darvish up in Cheyenne? Walks with a limp now."
Meanwhile, "Bounceback Cobb" sounds like a game that same selection of men might have played. But probably an unsavory sort of game that's responsible for keeping many a drinking and evening establishment open, dotting the edges of the western frontier like stars at the cusp of the space between galaxies.
All this talk of prospectors reminds me of the book A Moment in the Sun. The worst thing about that book is the title, but other than that, it's one of the finest books I've read. There's prospecting, gunfights, Teddy Roosevelt impersonations, genocides, Filipino revolutions, presidential assassinations, and one Native American character. And what's weird about the book is that it's historical fiction. The most bizarre, most offensive, most unbelievable things that happen in the story are true.
Well. You should read it.