Most ratsnakes I've encountered in the wild have been relatively docile, then again, I'm from Missouri, and all we have up here are black rats and great plains rats. I've never been bitten by a great plains rat, and I've only been bitten by a black rat once. Honestly, any time I've ever been snakebit, it was my fault. I even own a coachwhip that's only bitten me once, and that was without a doubt my fault, I was cleaning his cage and he was backed up into his hidebox, didn't see him back there, reached in, and he did what any normal snake would do, he let me have it.
I'm always wary of anyone with a snake that's known for a nasty disposition that they claim is "tame." Nine times out of ten it isn't tame, it's sick. I'll give you an example, close to my home is a pet store owned by a guy that I can't say enough bad things about, this guy literally makes me sick, sells retics, african rocks, burms, etc. to people who don't have a clue what they're doing. Anyway, at one point he had a white lipped python in there that he claimed was "tame." Recently, the store came over new management, and the white lip was still there. The people who took the store over took the poor little guy home for several months, nursing him back to health and fattening him up. I was just in there the other day to see what improvements they'd made on the place, and the little guy was in there. He'll gladly take a piece out of you now. And that's how a white lip should be. It's the same kind of thing with a "tame" tokay gecko, or a "tame" nile monitor, how many of these animals are truly "tame" and how many of them are just sick? It makes you wonder.
As far as yellow rats or texas rats go, all I can go on is what I've heard, and that's that they're nasty. Then again, I heard the exact same thing about coachwhips, and they've turned into some of my favorite snakes ever, very inquisitive, active, and not at all what I'd call "aggressive."
The only snake I've ever had that was downright nasty was a gopher snake. This snake was an absolute demon, and the only snake who ever went out of his way to bite me. I literally did everything I could for this snake, put him in a bigger tank, multiple hide spots, held him every day. Nothing, you could put your hand in this snake's cage and he would literally come flying out there ready to take your face off.
Then again, I've got another gopher snake now that's an angel, completely hand tame. Gotta love pituophis, they've got such personality from snake to snake.
I've had tame water snakes too, they're generally not too tough. Even had a tame blue racer once.
Kevin