Jamieson, Fausset and Brown on Titus 1:10

10. unruly--"insubordinate."

and--omitted in the oldest manuscripts. "There are many unruly persons, vain talkers, and deceivers"; "unruly" being predicated of both vain talkers and deceivers.

vain talkers--opposed to "holding fast the faithful word" (Tit 1:9). "Vain jangling" (1Ti 1:6); "foolish questions, unprofitable and vain" (Tit 3:9). The source of the evil was corrupted Judaism (Tit 1:14). Many Jews were then living in Crete, according to Josephus; so the Jewish leaven remained in some of them after conversion.

deceivers--literally, "deceivers of the minds of others" (Greek, Ga 6:3).