It's hard to suss out attitude, incuriosity, and/or inflexibility in the timeframe of an interview track. There's only so far those will hold a candidate back before they simply don't complete the interview of their own accord.

Red flags you're likely to encounter if you conduct interviews in the dozens are:

1. Don't know how to say they don't know. Have had candidates call up two screens and google the answers for questions they don't know, all while they're interviewing. (The eyes would give them away). The correct answer was "I don't know", not "let me google that for you".

2. Simple incompetence. They may be able to recite, rote, everything in the Android SDK documentation, but be unable to properly write a for loop. Almost makes you want to hire these people because the former is so rare to find, but, no.

3. Unrealistic expectations as to start date. Have had some great interviews where everything was perfect, but they wanted a year to travel before they would start (nothing against people from Europe, but, sigh..). I doubt that company even survived the full year.

4. Bait and switch. Apparently some devs contract out their end of the hiring process, paying "experts" a couple hundred bucks to interview under their name, get them the job, then on day 1, the interviewers and rank-and-file developers none the wiser, show up as a different person with the same name, without the requisite possibility to pass the interview or succeed in the workplace. They nod, smile, take on assignments, join the team at lunch, try maybe, but fail to deliver, and can glom on to the high-paying job for months before corporate axes them, never realizing the scam they were taken for.

Having been on both sides of the interview process far more than most, I firmly believe that the majority of the dysfunction in hiring software engineers is on the company side. Corporate monopsony breeds systemic incompetence in hiring.