Why Lazy Workers Are Often the Ones Complaining about the Job
"Usually, lazy workers are those who complain a lot about their jobs."
In Psychology, that behavioral mechanism is a combination of denial (deliberate or not) and projection.
The lazy person denies (or pretends to deny) that she is lazy and then complains about other coworkers (who may be lazy themselves or not)--projection--as in projecting their own shortcomings to others.
It is also a tactic--projecting the laziness on others so that the attention would be projected on the coworkers she is complaining about--in the process, covering for her own laziness.
In a workplace, observant managers and workers could easily spot who are the real lazy ones and to recognize such complaints as a defense mechanism of these lazy ones. Unfortunately, people who are lazy themselves couldn't recognize this; worse, managers who are oblivious of or unfamiliar with the daily routine undertaken by the frontline staff members easily fall for the complaints of these lazy workers.
This is also the reason lazy workers love a disorganized and unsystematic workplace or work routine, because without a proper working system in which task distribution and work performance could not be measured and clearly identified, lazy ones always get away with their laziness.