ComSonics interview questions

Interview was scheduled 24 hours after I applied, for the very next day, so they were very quick and responsive. Interview was on site, standard questions. The one question that stood out to me as a red flag was asking how to deal with a troublesome/aggressive coworker. While they didn't ask many questions, the fact they asked this says to me that this is such a recurring issue that they feel obligated to ask during an interview. The experience seemed mostly positive until the very end when I asked about payrate. The listing did not have it posted, but asked "what are your salary expectations?" in which I replied negotiable. When I asked in the interview, the attitude shifted negatively, and I was given a vague answer with a super low number. Later that day I was offered the position, but the pay was still super low. I gave a counter offer, in which they refused.