Coating with sugar and ruffling the feathers: signs that will make you think twice before accepting that job offer

Other than catching how "off" the job offer sounds, there are other signs that might indicate that something may be awry about the prospective employer or your prospective boss.

COATING THE PROBLEMS WITH SUGAR
If you get a chance to talk to someone at the company you got a job offer from, and if they say something that sounds like the following, you might want to flag those statements and further analyze (and try to get a second or even a third opinion if you can):

• What you hear: "X (your supervisor) is not the easiest person to work with"
  What this could mean: X is a royal pain to work with.
• What you hear: "X can be insensitive"
  What this could mean: X makes wildly inappropriate remarks often.
• What you hear: "X is excitable and full of energy"
  What this could mean: X is highly irritable, with possible yelling and expletives.
• What you hear: "Sometimes"
  What this could mean: This depends on how the "sometimes" is used with other statements. "Sometimes" used concurrently with "excitable" could imply that the person yells at employees on a weekly basis.
• What you hear: various "X-hack" tips and tricks
  What this could mean: X is "not the easiest person to work with" to the point where hacks needed to be developed.

Sometimes, people actually say what they mean (e.g. X is not the easiest person to work with but is not a royal pain). But sometimes, it could be a form of a coping mechanism - they say things in a way that convinces themselves that they're working in the right place (even though they're actually suffering).

RUFFLING THE FEATHERS
The other place to look for signs is X (your prospective supervisor). If they consistently exhibit the following behaviors, you might want to think twice before committing to work for that person:

• What you hear: Bragging about their accomplishments
  What this could mean: Fear of losing "face"; the need to stroke their ego
• What you hear: Lecturing about any and every​ subject
  What this could mean: Lack of self-awareness of what they know vs. what they don't know. This can potentially harm the business' decision-making (if they insist on making a decision on something they have no expertise on)
• What you hear: In an argument, they start with one side but suddenly switch sides when they realize they're wrong, e.g. "(after switching sides) Exactly, that was what I meant" or "That was what I always thought"
  What this could mean: Not mature enough to admit mistakes. They also argue for the purpose of winning (they'll switch sides as long as they can win!) and feel too insecure to "lose a battle"
• What you hear: Calling someone who is reacting normally to a stress-inducing situation "crazy" or "mentally ill"
  What this could mean: Alarmingly low mental health literacy; could be a proponent of mental health stigma in the organization (willingly or accidentally)
• What you hear: >90% talking, <5% listening
  What this could mean: Unwillingness to listen to others or not accustomed to listening to others

If you see a combination of multiple signs, my personal recommendation is to respectfully decline the offer and look for somewhere/someone else (to me, at least, the who you work with is as important as what you work on). But if you think the benefits outweigh the costs, go for it and carpe diem!