Don't be this guy!...
When I walk into commercial gyms I almost need blinkers on. It saddens me to see SO many people doing ridiculous movements either with or without weights. It is more about HOW they are doing the movement than WHAT the movement is.
So many out there don't really know what is good for THEIR body, one movement may be good for one person but detrimental to another. It is all relative to where your body is at at the time, what your history is and what your goals are.
If you are someone looking to join a gym to workout regularly then please please please get assessed by someone who knows about movement and is more highly qualified than just a Cert IV in fitness (the basic minimum personal training qualification).
Injuries happen when you're least aware about them. A repeatedly poor movement pattern can take weeks/months/years to show itself in the form of pain/stiffness which inevitably becomes chronic pain or stiffness if not dealt with and reversed.