Depends, I'm reliably informed, on how much one takes. (Both at a given time, and overall.) There's a fair amount of mythology about crystal meth, just as there is about crack cocaine. I'm told that it is entirely possible for many people to use both recreationally and occasionally without suffering severe consequences. One of the problems we have in the society in understanding what the effects of illegal drugs are is that most of the research has been done with addicts, usually those who have fallen afoul of the legal system. Imagine what the popular picture of the use of alcohol would be if most or all of the research and popular image of its use was based on alcoholics. (I'm not, just to be clear, advocating the use of crystal math, although in my younger days I was known to cram for finals with a beer and Benzedrine in my system, every now and then.)

There are those who can use drugs, including alcohol, without getting addicted.
Most people use alcohol and are not alcoholics. Not as sure about meth or crack- if it's more common to get addicted vs not.
This came up on the KQ morning show today. Several people called in saying they used both meth and crack for years without getting addicted, and quit without any problem.
Except for the damage done to your mind and body by ingesting all those toxic substances used to make meth. Ever see the remains of a meth lab? No wonder they are so expensive to clean up.

It's very common for the production of chemical substances to require some pretty awful-to-be-around processes. The reason why there's so much trouble with meth labs is that while the processes produce a whole lot of awful residues, they're pretty simple and straightforward -- it's possible to cook up meth pretty much anywhere, if you don't care about what chemicals you are around. Doesn't have a lot to do with the end results -- the same thing is true for the processes to make many things. The difference, of course, is that most chemical production takes place in places that have good -- and expensive -- ways of protecting the workers from the environment around them.

The fact that he is trained in recognizing the symptoms of someone using meth

You're assuming that the use of math will necessarily produce recognizable "symptoms." What is the basis for your assumption?

The basis for my assumption is that I personally have worked along side people who use meth, as I am a carpenter and drug use is still prevelant in my trade, and the symptoms appear to me quite obvious. Especially if the use has been for any period of time. They start with the obvious no need for sleep for 2 to 3 days while they do what is reffered to as tweaking. This is where they do the same activity, be it cleaning, working ie; sheetrocking or roofing, which are prevelant in my line of work, and they can do more of it without getting tired. The continued rise in meth use and arrests should have given a long time police officer some experience in arresting someone who is using. Also one would think there would be some behavioral changes since the son reported that "Noel told authorities that he often got high his mother, and that he smoked, snorted and ate the drug while his brother and mother usually snorted it, the documents said. " The key word being often implying that the use was more than recreational. Also the fact that they where indeed buying more meth and the mother stated she would probably test positive implying that she must have used recently.

The use of "math" will generally produce recognizable symptoms, depending on the application. Say, accounting, engineering, etc...