First I had three phone interviews. Each was meant to go for 15-20min, and each went for over an hour. I took it for a good sign, that they like what they hear and wanna know more. Then they flew me there for the interview. The reimbursement was easy and they got the tickets, car rental and hotel. Very nice up to that point. But once I arrived on-site it was an 'XXX-hole show' beginning to end. The front desk people were sort-of rude, definitely not pleasant.
I was asked to give a technical presentation and they said that their staff is highly technical and I should dive into details, it will not be over their heads. So I did. And no-one understood what I was talking about. (what was I thinking?!?!)
Then they took me to lunch and a quick tour to wow me with their cool toys. I definitely got a feel then, that the company is run by recent undergrads that think rockets are cool, with little regard to their own private lives, hobbies and outside-of-work passions. And it was clear they had little regard to mine.
And then we went on to cross-fire questioning. They were rude and did their best to make it stressful. At that point I gave up on them (and decided not to take the offer if they extend one to me) but kept answering their stupid questions.
A while later they offered me the job, and I said 'no'. Had another offer at that point, which I gladly took. I'm paid better, better benefits and a ton of other perks (including a pretty much stress-free work environment).