I consider myself to be an anti-bullshitter. I once said in a job interview that I knew nothing about the technology they were hiring for, but I was pretty sure I could take a decent stab at it.
I was telling the truth.
I got the job.
I was telling the truth.
I got the job.
I've seen this in interviews too, but my experience on this response is a bit mixed. I appreciate the honesty, but saying you don't know is a dead-end to solving the problem. A better response would be "I don't know X, but it sounds similar to Y which I solved by ...". Even if X and Y are not closely related, it at least shows they have the ability to make these mental connections.
Saying "I don't know" is one thing - it's good to admit one's lack of knowledge.
Being able to then follow it up with the will to expand their knowledge - that is valuable IMHO.
I make my competence on a subject clear. Ie. Did an assignment using this tool or read a few blogs so am aware of it and that's it. But a surprising number of times the problem isn't thay difficult despite my ignorance about it. You can often find a very close analogue to the unknown thing and then take it from there or let the tool itself function as a black box and design the requested system around it.
The plain "I don't know" - er while noble, can often be mistaken for incompetent when every other bulshitter claims to know it all.
* comparison to other candidates * truthfulness/honesty * track record * personality
At some point, the "I know nothing about this" really isn't all that true, especially for senior dev folks. I'm not sure there's much tech I couldn't say "I know nothing about X", because I understand fundamentals. I don't know much about a lot of tech - erlang/lisp/rust all spring to mind. But I understand variables, scoping, order of operations, etc - even if the behaviour is somewhat different from what I'm used to, I know some fundamentals that I didn't know in the beginning (or... were not muscle memory on day one).