It depends on what you are trying to achieve and how bad it actually was and how typical those conditions are for your industry or profession.
I had a job where the shortest day I worked was 11 hours and the most common was 18 hours and I worked every weekend for 4 months. Since I didn't want to get into that type of situation again, I was open about the working conditions having changed to ones that were not acceptable and I described what I was trying to avoid.
I had no problems with anyone finding it unacceptable to want to leave those conditions. I made sure they understood, I was open to working appropriate overtime, but not to make my job be the only thing I did except sleep. I pointed out that I wasn't mad at the company, just that the organization culture was one I did not wish to continue in. If you choose to disclose the corporate culture you don;t want to be in, it has to be presented in such a way that you are not bad-mouthing the company. It is one thing to say, "The workload evolved until it reached a level I personally could not sustain." and it is another to say, " I hated every minute of working for company ABC because they never let me go home and sleep but the %^#& managers always left on time." If the work conditions are truly ones you don't want again, then letting people know that is not a problem as long as you accept than some employers might also be that bad and you will lose that opportunity. I personally see that as a plus. YMMV.
However, if I have been working say 50 hours which is fairly typical from my industry, it would have been more of a concern. In that case I would have fallen back on the old standby of looking for more opportunities to grow my skills or greater opportunity for advancement both of which are always acceptable answers to the question.