we see it all the time:
swimming with hands nearly as much as fins.
fast rapid movements with arms body and legs.
fast movements with lights.
pointing light at peoples faces.
hitting bottom, stiring up dirt.
wrong fin technique near bottom or other dirty surfaces.
touching and braking corals.
picking up animal life with no or little knowledge about it.
bc expand and fast accent, forget to handle this at erly stage.
wrong weight, so end of dive is at surface.
Gauges and Octo dangling in sand and dirt.
wrong position of tank valve, and also of 1. regulator.
hoses tangled in bc.
jumping from boat with missing parts, or parts not ok.
enter and exit from rib-boat always look dumb when not skilled in it.
forget to bring important equipment from home to dive site, and need to ask for loaners (embarising)
I dont say I am much better, just a little bit offcourse
I know I have done all this, even several times.
the more trained you are, the more you see those kind of ignoring details from others,
and the more you try not to do it again your self.
Let beginners be beginners, dont try to make DM out of them in 2 days,
explain nice and friendly how to improve the details you see are not perfected,
and even show them slowly when needed, they will most likely listen and learn, and you get new friends,
do NOT play king-smart or arrogant, in water/boats or even on forums, those kind of divers makes many mad,
it is ok to know better, but if you can not share your wisdom in a good and positive way, dont !