If HA has a chance of being passed, the chance is always 60%.
The ability, like the species, is determined by the female. Meaning, HA can only be obtained using a female parent with HA. If the female does not have HA, then the chance for the offspring to obtain HA is 0% regardless of what ability the male has.
Using Ditto doesn't change that, except that breeding a male Pokemon with a Ditto results in the male effectively being treated as a female for the purpose of passing species and ability.
Long story short:
(Same species) HA male + female (no HA) = no chance of HA
(Different species) HA male + female (no HA) = no chance of HA
HA male + HA female = 60% chance of HA, 20% of ability 1, 20% of ability 2
Male (no HA) + HA female = 60% chance of HA, 20% of ability 1, 20% of ability 2
Bonus:
HA male + Ditto = 60% chance of HA, 20% of ability 1, 20% of ability 2
(The last one is the source of much confusion; even Bulbapedia is wrong. However, I am 100% sure of my claim as I have tested it myself, and so has Cu3PO42.)