Apart from these, we can also check the way logbooks/reports are scribbled or made and this too can give a hint about the type of person we are examining. If details are not included or are evasive or little, this may be an indication that the person is either not attentive or there is something hidden.
The same may be the case with respect to handwriting. Several years ago, I had gone through a book on graphology where it is stated that the opinion of graphologists is taken into account by the court of law for the land.
Maybe we have to observe the manner in which a person talks (face reading).
And, then coupled with our knowledge and experience, we can have an assessment of the persons engaged in the shopfloor and take a decision on whether to continue or change the person for good.