From experience, they seem to heal well generally. I guess thats the nature of having an open wound, all the pus and crap can drain out. The positive pressure of the pack apparently promotes granulation (healing).
In the bad old days, they used to use "EUSOL"- Edinburgh Solution of Lime. (Basically bleach). The last time I packed one (many years ago), it seemed to be a little more gentle (seaweed or silver based dressings).
We used to try and time things around your bowel movement (rather the other way round!), and asked the patient to have a bath or shower prior to the dressing change.
Another tip is to make sure the nurse gives the pack a good squirting with sterile saline a few minutes before, the pack can sometimes dry up overnight.
Watch out for over zealous nurses "swabbing" the wound for laboratory analysis (it's a nursey thing)-shouldn't really be done unless there's clinical signs of infection. They all look a bit pussy and smelly, generally you only need to treat if inflamation is spreading to surrounding tissues or if you are unwell. (Unusual).
It is many moons since I repacked a moon, so check with your friendly DN.