Green’s Dictionary of Slang

a bad sort, an unpleasant person.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1873		Sl. Dict.
1882		Sydney Sl. Dict. (2 edn) 11: Dab tros - Bad sort.
a.1909		press cutting in J. Ware Passing Eng. of the Victorian Era 115/1: If a chap happens to be a dab tros he gets on better than a doogheno who keeps himself quiet and never lets anybody Tommy Tripe know how clever he is.
1999		G. Seal Lingo 41: Thus the police became esclops, delo nammow is an old woman and a bad sort became a dob tros.