I have owned/trained many horses of different breeds, ages and gender and haven't had a bad experience with a mare due to her being in season or being badly mannered towards other horses or people. Perhaps I just haven't come across a truly hormonal mare yet.
Although I have certainly had my fair share of mares that exhibit some bad behaviours, I have found it has always been related to poor training or lack of work/proper upkeep. The best horse I have ever owned is a mare, I have owned her for over ten years now and never found her to be a problem when she was in heat, even when riding in the company of stallions or other mares. Perhaps she was an exception.
So tell me your stories about your mares, whether they are good or bad, I am interested to hear!