Arseholes are everywhere OP, but I've been a member of many gyms and there are definite variations.
I use to power lift (I still weight train) and as a stocky but reasonably slim woman in my late 20s at the time, got abuse from the student body builders just for having the audacity to use a squat rack or a lifting platform.
When I was very slim, I constantly had people telling me I couldn't lift heavy objects. If I showed them I could, I was going to get musclebound or 'manly' (I'm 5' and large of bust 
) On the other hand I have always been a rubbish runner but would get incredulous 'I thought you were fit?' at my mediocre 5k times.
A few years ago I got ill, had to take loads of steroids and gained weight. My body shape changed and I couldn't exercise. It's taken me nearly twice as long to get back to previous fitness as it took to lose it. I'm still overweight, but I do endurance cycling, running, yoga and weights.
Today, some morbidly obese people who were eating chips shouted at me in my - admittedly ludicrous - hot pink cycle gear. A couple of weeks ago, a young skinny lad smoking a fag shouted that I'd have to wring my knickers out 
when I was cycling in the rain with DP and he was driving past. No-one shouts at DP. No-one comments on DP in fact. When I out-bench him (which I do) no-one says he's relatively weak in that area (he'd admit it himself), they say I'm freakish because I'm a woman
I did a work cycle challenge and had people congratulating me on doing 30 mins on a spin bike. Even people suggesting I was looking stiff the next day. I can cycle over 100k at a stretch at a reasonable pace for an amateur, but I guess I don't look the part...just as I didn't look the part as a skinny powerlifter or a middle sized woman in an Olympic lifting gym.
Anyway, my point in this saga is that there are a lot of cunts out there. Really, a lot of cunts. Fat ones, thin ones. I've become very disheartened at times listening to the buggers, so hard as it is, nowadays I genuinely don't. I use a heart rate monitor and online tools to compete with myself. I measure my weights and reps. I try very very hard not to give a flying fuck about what other people think.
Oh an when I see the morbidly obese woman that comes to my spin class every week I think 'good on you' because I saw her when she started while she's got a long way to go, the progress she's made is absolutely incredible and she's better at keeping up with the instructor than some of the skinny poseurs who I've also cycled behind.