Was changing a flat with the kit in my car, the scissor jack it came with was so improperly rated for the load that the bolt bent and the whole thing fell apart, sending the rotor straight into some dirt. Luckily enough nothing got damaged, but it still took 30 minutes to get that poor thing off the ground with a real jack and bricks. It was such a low rider that we had to start from the back and creep forward.
Never using a scissor jack ever again, and I've heard enough horror stories from mechanics about not using a jack stand that I will exclusively be using them if the things off the ground for any amount of time.