Has anyone ever considered what really would happen if Ranma found a cursed drowned man and jumped in it? Really, the end result would likely not be what Ranma expects it to be. All one has to do is consider what happened to Pantyhose Taro when he used the water of another cursed spring on the cursed form he already had, bathing in another spring gave him tentacles on his transformed states back, it's that thought in mind that makes sure that Ranma would learn to regret using the spring of drowned man if found. If Ranma really did bath in a spring of drowned man male characteristics would blend together with his female form, the result would end with Ranma becoming an androgynous of some kind when ever he gets hit with cold water.
If you need a good example, look of the myth of Hermaphroditus.