Commiserations

I had another shitty day at work the other day (and again today) and when I got home, friends and I got into a chat about bad bosses we'd had. For a while it was good to laugh and commiserate, then we watched Horrible Bosses. That helped to put things into perspective and lightened my frustration. But I find myself wondering how much sharing of woes is good. When does it become futile or whinging?