To the posters who say Lulu Lemon shorts outlast their other shorts, I find this very surprising. I've never thrown out running shorts and the only shorts I've ever seen get super ratty were Under Armour spandex I raced in in high school because our team didn't want to run in briefs and the first pair of running shorts I ever bought and they got destroyed because when I started running I had like 3 pairs of actual running shorts and ran in cotton Soffee shorts the other 4 days of the week. I've never run mega-miles but I sweat a lot and I went long stints of 2x a day aqua jogging in college and leaving my clothes sitting around soaked in chlorine for a week or so.
I don't know about the magical ass thing and the yoga pants. As an actual runner, I never wear yoga pants but many of my running tights do fit very well but I also have pairs that sag and don't stay up. I'm also runner skinny so any leggings that are not too big on me are probably going to make my butt look nice. If I was a slightly overweight middle-aged women it'd probably be a different case. I also need too much athletic clothing to justify spending Lulu Lemon prices on it. I also regularly wear Nike Legend tights and matte Under Armour leggings with normal clothing and no one seems to notice that I'm wearing running tights as if they were non-athletic leggings.