It obviously depends on the person and the circumstances. Whatever goes on in your personal life, you have to be focused and present, in the moment, when playing poker if you want to play well.
Some people play poker as an escape (could be in a good way) in the sense that it takes their mind off of their life problems and gives them something to do in the moment. For this type of person, they might enjoy playing poker after something sad because it helps take their mind off of it temporarily.
Conversely, some people must be motivated in all aspects of life before bringing that to their poker. These personalities wouldn't be able to play poker well if they were sad, or whatever else in life wasn't in order.
I think it ultimately comes down to how you think your feelings going into the game would impact your play. In the case of feeling sad going into the game, you would have to determine for yourself if this would negatively impact your
poker game or if you could still play your best poker.
That would determine if you should be playing poker or not, but you must be in the right state of mind to play if you want good long-term results.