I went to a coed gym that I really liked, but when I had problems with other patrons, it was always with male patrons.
There was all manner of inappropriate behavior by men. Some were oglers. Some were exhibitionists–there was one guy who would wear shorts so loose that they would fall down off his butt when he did stretches…always in front of a row of women on exercise machines. Another guy would wear tight, short white shorts with no underwear and do stretches in front of the whole room, showing off his goodies for an hour or so. Then there were the young guys who would loudly and crudely discuss the various attributes of the women in the gym.
Men sometimes made it really difficult to use the weight machines. They would come into that room in groups, get loud and crude with their conversations, and hassle me to “hurry up” and finish using the machines, even though I was not loitering.
I had men walk past me when I was working out on the cardio machines and make rude comments about my workout. One guy laughed at me because I was sweating so much.
In the swimming pool, the men would refuse to lane-share with other men. (OMG they might catch teh gay!!!) Instead, they would insist on sharing lanes with women, even if those women were swimming at a much slower pace. They would not share nicely, either, but would hog the lane, or pass me without caution, hitting me with their arms and legs. The swimming pool was used mostly by much older women who were there to do water aerobics (which was allowed in the far right lane all day long). Men would come in and tell those women they “had to get out of the pool” so they could swim laps (totally not true). I found out that the evening water aerobics classes were sparsely attended because men would sit at the side of the pool and loudly complain about the lanes being taken up and comment about the physiques of the women participating.
I actually had trouble with a male trainer, too. I met with him to ask questions about a class he was teaching, to find out if it was right for me. He asked what I was looking for. I specifically told him that I did not like running, especially not outside. I had a knee injury that can’t take the impact, and outdoor exercise is more likely to trigger my asthma. He told me to come to the class for a free session and that he thought I would really like it. The very first thing he did in the class was take everyone for a long run outdoors. I quit right then and there. He called me up later to find out why I’d left. I told him, and he “mansplained” to me that I was wrong about not wanting to run outside and that he knew better, that I really needed to do it. Sorry, no. The female trainers always listened to what I wanted and gave good advice about exercises.
There is no female-only gym here in my town, but I desperately wish there was one. They exist because a significant proportion of the male population behaves badly at co-ed gyms.