Answer:
unkempt and smelly
Step-by-step explanation:
The expression refers to two people that are, from the authors point of view, in need of hygienic attention. The expression ragged as a jay-bird is usually used to refer to people who do no take care of or wash themselves.
In this excerpt, the comment could also be direct at the state of poverty of the man and his son as they may not have the means to care for themselves as society would expect.