I have found my scientific health book. My scanner is broken, so no illustrations.
Standing Toe Touch
"Puts excessive strain on the spine."
Standing Ankle-to-Buttocks Quadriceps Stretch
"Puts excessive strain on the ligaments of the knee." If I had a nickel for every time I saw someone do this at the track...
Full Squat
"Puts excessive strain on the ankles, knees, and spine."
Prone Arch
"Puts excessive strain on the spine, knees, and shoulders."
Standing Hamstring Stretch
"Puts excessive strain on the knee and lower back." (Ditto for seeing people do this at the track.)
Yoga Plow
"Puts excessive strain on the neck, shoulders, and back."
Hurdler Stretch
"Turning out the bent leg can put excessive strain on the ligaments of the knee." (Did I mention the track?)
Neck Circles
"Puts excessive strain on the neck and cervical disks."
~
And with that, another funny thing is that stretching before a workout can decrease muscular performance by "5%" according to some study (my health book is from 2004, though). Yet in every athletic sport I attend, I see stretching take place before the game begins under the guise of "warming up", which is totally misguided. Warming up means physically raising your temperature through exertion to a level of activity conducive to exercise, not tearing your muscles so they'll heal more flexibly in a couple days (which is, of course, stretching). Stretching is to be done after the workout, and the benefits of flexibility and range of motion manifest in weeks after implementing a stretching routine.