Great thread! I actually enjoy the clothes in workout videos; wearing cute (not necessarily Athleta catalogue cute, but I mean bright, colorful, cheery) workout clothes is a big motivator for me personally, and it's fun to work out with instructors who are also dressed cheerfully. It also helps me remember what workout I'm doing ("Oh, yeah--this is the one where Cindy wears the yellow top. That means mountain climbers!").
That said, a couple things are turn-offs...
1.)
Instructors/cast who seem to have forgotten they were going to be on TV. I get wearing something comfortable, but sloppy, dirty, old, stained? Really? You couldn't bother to show up for work in professional attire? The worst offender here is Jillian Michaels in 30 Day Shred. She wears a ratty old pair of sweatpant capris WITH A HOLE IN THE WAISTBAND!
(Also, the crazy-print pants she wears in her new set are kind of distracting...and I kind of like them at the same time. LOL)
2.)
Instructors wearing things that I would find uncomfortable. Call it a mirror neuron thing, but if you're wearing loose, baggy clothing, I'm going to feel like I'm wearing loose, baggy clothing, and I can't work out like that. This is a major reason I can't try Zumba--those outfits look awful--pants you could trip over, way too many unzipped jackets flapping around... I know it's part of the "mood," but it just does not work for me at all! There's also something Alison wears in one of her Firm Express workouts--a cropped T-shirt with a really wide neckline. I keep wondering what happened to her bra and worrying that the top is going to slip off. If I were wearing that, I'd be way too distracted to get anything done.
3.
Clothes where you can't see the form well. This is probably the only significant/
legitimate complaint that I have.
I tried a barre workout (it might have been Pure Barre?) where the instructors were wearing black pants and black socks and working out in front of a black studio wall, and I just couldn't see what they were doing AT ALL! In cardio or weights it's not such a big deal, but in barre when tiny adjustments of form have a major impact on the quality of the workout, yeah. I Joni-O'd that one and never looked back.
4.) Male instructors where you see too much. My DH is a pop culture blogger and just covered cosplay at a Con... his major comment was, "Guys, if you're dressing like a superhero [ie, in tight spandex], you have to wear a cup!!" I have a Gaiam foam roller video, and the camera operator must have had a crush on the instructor, b/c there are a lot of... uncomfortable closeups. You know foam rolling--lots of movement around the hips/IT band? Didn't need that many closeups... for that long... yeah.