What does a bad voltage regulator look like?
There's no reason a defective IC should produce any white substance when it fails.

In fact, unless the part failed under spectacular circumstances, there's usually no visual indication that a part is bad. Sometimes they will be visibly blackened if they overheat, or tiny drops of clear liquid will exude out from the packaging encapsulant. Or the markings on the part may fade from heat, but that can also happen just from long normal usage, especially with hot parts like voltage regulators. 

The most likely thing I can think of is, if the part comes out of some old equipment, it had some silicone grease on it to improve contact with a heat sink. When that grease gets old and dried out it can look something like leaking battery gunk.