Corn snakes, milk snakes and king snakes are not know to be heavy soakers although some do.
If all your husbandry is up to par I would say the problem lays with the husbandry skills of the pervious owner.
A lot of snakes that have had bad sheds due to bad husbandry will continue to do so even after the animals environment has been brought up to par.
With the snake in a proper environment its issue should get better and better with each shed.
I am currently working on a similar issue with my Mexican Black King. He is on this third shed with me and still has problems. On his last shed, the last 3/4 of his body shed fine but his first 1/4 on the top of his head and back did not. I simply held him with a warm damp cloth over him for about 15mins and then put him back in his enclosure. After he burrowed around for a few minutes the rest came off fine.
With each of his sheds he gets better. Due to scare on his head I don't expect him ever to have a "GOOD" shed unless the scares completely go away in time.
Hope this helps.