My experience matches other people here. 3/4 of the interviewers were good but that 1/4 ruins everything. My last round was this guy who was clearly not interested in conducting the interview. He asked me a question and just sat there. He didn't engage, was very cold to questions and I had no clue if I was on the right track.

As an interviewer myself and having interviewed for startups (which is a different beast due to the additional selling involved in converting candidates) I've learnt to break the ice, encourage the candidates, treat them as human and guide them towards the solution if they're off by a little. I do also cut short some interviews when I realise the candidate is an obvious mismatch. I do so politely and in the interest of saving both of us some time.

So, when the Airbnbs, Dropboxes and Googles don't extend the same courtesy - even though I know they have the upper hand - I lose any interest I have in joining them by the end of the interview. I have had really good experience with BrainTree & Pinterest & a few others. So I do know not all companies are bad and even within the company there are good and bad interviewers and it's just a matter of luck. Still, the doubts about self-worth are hard to squash.

Edit: I call out Braintree in particular because they conduct interviews in pairs. At least one person's job to listen at all times. IMHO, this makes all the difference. Any signs of bias, narrow perspectives and hostile behaviour should - at least to some degree - be reduced with this model.