A soak in warm water won't do them any harm, will probably encourage them to drink and eliminate. It depends on the individual snake's temperament--if they really hate it, and they're shy, then don't do it unless you need to in order to remove dirt or a bad shed.

Don't use soap, of course.

A lot of balls kept in captivity are kept at a humidity lower than what they really need. These snakes are usually dehydrated (which is what causes a bad shed--you shouldn't just raise the humidity when they're opaque, they need it over 60% all the time). So, some extra drinking water isn't a bad thing.