Neuroscientists have found that listening to a complainer for a half an hour or more "peels away neurons in the brain's hippocampus". Hm? I'm thinking that might be a problem... given that the hippocampus is the part of our brain that we use for problem solving.
http://www.inc.com/minda-zetlin/listening-to-complainers-is-bad-for-your-brain.html