Even if the product has been running flawlessly in production for 5+ years?
"Proven in use" and backwards compatibility is a bitch.
Well, if it's a library function like printLine and it does something else instead of printing to the console, that's probably a mistake (though if it does something so wildly different it cannot be simply a bug, for example logging to a file, I'd still wonder if the name is wrong). The problem is that you can't generalize this reasoning. For example:
def sumAllNumbers(nums: List[Int]): Int = {
nums.filter(_ % 2 == 0).sum
}
So the name definitely helps, but it's not conclusive.
I don't know about you but I certainly know that if a printLine function accidentally does something else, it's definitely the code that's wrong and not the function name.