In my master bathroom, I've recently removed some door trim that appeared to have dry-rot at the bottom in order to replace it with new trim. Upon removal, I can see (using a flashlight) that some of the wood faming appears moist and is black. The location in the bathroom is the wall between the master shower and the water closet and my suspicion is that there is some sort of slow leak in the plumbing inside the wall and that it has caused the wood framing to deteriorate. My plan is to tear out the shower walls (cultured marble) and replace with tile but I'm afraid there may be black mold growing in the wall. I've heard horror stories about black mold so, before I begin tearing out the old stuff, I need some advise on dealing with the potential of black mold. Is this really as bad as some say? What precautions should I take when tearing out the old shower walls?

There are many types of mold and most appear blackish so don't jump to any conclusions just yet. You can buy a mold test kit at most hardware store and have it tested. I would do this before tearing out anything. You can Google MOLD TESTING and get several sites like this Family First Environmental Corp.® Once you have the test results come back and we can help you with the tear out, fix and replacement.

Here is a helpful link from the Centers for Disease Control:

CDC - Mold - General Information - Basic Facts

The mold hysteria is largely just that: hysteria with no basic in fact.

Testing for mold is usually without merit since there are no standards as to the health hazards associated between mold species.