How do you determine the root cause of another sims feelings during conversations?

A lot of times it's just a buff given to non played sims and there is no reason. I've checked buffs before using MCCC and it will sometimes say things like stressed event or sad event so, basically meaningless. However if they are uncomfortable you can almost guarantee it's either because they are over heating, cold, uncomfortably wet, or if they are very sad it's almost always because they are mourning. Although, they could also be stressed because they saw an unpleasant lamp or mailbox... like that makes any sense. :D