I've had two bismarks - one old one that's not marked dovo (but is similar to the current shoulderless style) and one new one that I bought a couple of years ago. The old one is straight, and the newer one was not straight, which made it a but more of a pain to hone. Both took a good edge, though.

I have had two razors, though, that refused to take a good edge. One was a sheffield W&B razor, and the other was a japanese razor with nice spine work. The second of those two is sitting in my trash can. I tried everything I could to save it, even bringing it to straw temper hoping that it was just overhard, and it refused before that to take a good edge and it gets an edge very similar afterward.

The straightness issue is one of the reasons, I believe, that the well known cutlers razors bring money. The vintage razors that are precisely ground and a bit dressy from a known maker have been straighter in my experience than razors that don't have the same pedigree. I'm sure it's not a 100% bet, but in my experience, it puts the odds in your favor a little more. A cutler straightens those razors by eye (and using a hammer) as part of the grinding process, it's a skill that takes time and effort to learn and apply, I'm sure.