1- Ask the interviewer that how long is the lunch break? 1 Hour means good, 30 minutes ok and 10–15 minutes means red flag. Visit that company during lunch break to see if people are really enjoying free time? 

2- Pantry facilities.(This matters as weirdo companies give only water but real good companies keep tea coffee milk water and other things in pantry). Just ask if they have equipped pantry)?

3- Do they ever call on weekends. Never means good but sometimes means they are snooty and blood suckers.

4- How they treat an employee if he takes emergency leave two times in a month for genuine reason? Ask it. And check the face of HR interviewer. You will get the answer.

5- If interview is in office itself check the dressing sense of the people walking around. Highly sophisticated means they are happy. Shabby means they are coming for just money, not enjoying work culture and working at lowest encouragement.

6- Check the interviewer’s own face and body language too. If he is crisp, happily smiling often and wearing nice clothes with good shoes, he is with good company. If he is extra strict and very proud and snooty that means he is getting quite good company and feels proud of being there. Commitment comes from good financial situations and less stress.

7- And best part is to check how females are in that office? Females are always happy heart. If they are getting paid on time and get good salaries and comfortable but highly disciplined working they pay for self dressing and looks. If they are looking shabby trust me they are under high stress.

8- Check for the helping staff around, if no-one around that means a lot but if lot many helpers around serving tea and coffee this shows they want their employees to focus and work more.

9- Last but most important thing, when you go for the interview check the cars in the parking lot. Males generally buy good cars if they are getting good salaries that too on time. 

10- Chairs. Last point. Check which kind of chairs they are providing to their staff? If it is very good and comfortable, they care and might be taking lot of work. Interior designers suggest now a days that chair is one of the major point to give a person that feel of not getting up early. But if the chairs are very bad and cheap, no matter what package they are offering to you, your health is going to suffer very badly.

11- Females and males. Well dressed up females means they are giving good packages, extra well dressed males means there is loads of politics and performance/work pressure in the atmosphere.