How's the form?

So many times - in fact nearly every time I go to the gym I see some clown swinging equipment around and if you were to add some flames to the weights it would make a good circus act!
One guy I have observed spends a couple of hours or more going around the gym in a circuit where he performs this mad routine.
I've seen where he carries out an exercise lying face down on a bench making movements like train wheels going around with his arms using dumbbells.
He then goes on to perform a swinging act with a set of dumbbells over his head and flicks them in to the air at the top of the movement catching them on the way down.
He then progresses on to pull the cable on the lat pulldown machine up and down as fast as he can.
He repeats this circuit over and over.
Have these type of folk been ill informed?
What muscle groups are they targeting?
Have they missed out on correct induction processes?
How have they formed these bad habits and poor techniques?
Any people that I see badly performing exercises with strange techniques in bad form seem to physically look the same year after year, never progressing.
They could be wasting hours of their life every week with unproductive workouts.
We all continuously learn, I have mentioned before that I have been inspired by Mike Matthew's Muscle for Life program and how I have changed my workouts around to prioritising basic compound movements as the first exercise for each bodypart. This has made physical improvements for me and I have got even stronger whilst dropping bodyfat. It's never too late to change our approach to training!
So how's the form?
Risks

Hoisting equipment around with a lot more than weight than you can handle with bad technique is not only unproductive but can be detrimental, can cause injury and even be dangerous.
Ego training

Perhaps one of the main causes of bad exercise technique is the fear of what others may think if you can't lift as heavy as them. It's like there is a hierarchy struggle at the gym!
Good technique however with a manageable weight will create a progressive resistance environment and strength will actually increase in a shorter time period. Don't worry about what others think, train with a weight you can actually handle with proper form.
Rep speed

Speed of movement is another aspect I see quite often executed badly with free weight and machine equipment being moved around by people at really high speed. Momentum seems to be moving the weight and not the targeted muscle group. Not only is this taking focus away from the target muscle, it is also placing a lot of strain on the surrounding ligaments and tendons.
Slow down - use a mind muscle connection, focus on the muscle from within your brain and feel the effect of the movement on that muscle squeezing with the contractions.
The positive portion of the movement can be more explosive than the negative yet should not be performed too fast. The negative portion of the movement is being absorbed by the tendons and ligaments and this should be performed slower than the positive portion with good control over the weight. This control over the negative potion of the movement may even be beneficial to imposing the right sort of stress needed on the target muscle and not the surrounding ligaments and tendons.
Go lighter!

Lifting heavy weight will increase musculature over time but this should not be done at the expense of adverse consequences such as muscle tears or ligament/tendon damage.
By dropping the weight and performing the exercise at the correct speed, using proper beginning and end points and eliminating momentum, this can be even more taxing to the target muscle. Over a period of time lifting performance should increase safely to above what was being attempted with incorrect form.
Train within your limits

I advocate incorporating low volume - high intensity workouts, some however may prefer utilising higher volume with less weight. I don't see the point however in spending hours in the gym with unproductive numbers of sets. Try a quality approach with good technique using manageable weight and I'm sure you will see results!