Angels are holy but they lack the perfection found in God

Job 14:17, 18  If God places no trust in his servants, if he charges his angels with error, how much more those who live in houses of clay, whose foundations are in the dust, who are crushed more readily than a moth! 
Job 15:15, 16 If God places no trust in his holy ones, if even the heavens are not pure in his eyes, how much less mortals, who are vile and corrupt, who drink up evil like water! 
These parallel verses are spoken by Eliphaz the Temanite who does say things that are incorrect and so these verses may be unreliable. It may be wiser to say that Eliphaz does state a truth here and that is that although there is a holiness about the angels that is far above the greatest examples of holiness among men, nevertheless it is less than the holiness of God. He can discern an imperfection even in the holy angels.