I've been wearing it for the last couple of weeks while I've been in hiding and I have to say it's certainly done the trick. I've not been mithered by any of the people I've been hiding from.
For proof they work, see this. You'll have to look very hard, but if you concentrate you can see a mass-murdering war criminal hiding in plain sight ON THE TELLY.
Perhaps the Portugeuse police are on to this, but it's all gone terribly wrong. Maybe they've been confused because they've been looking for a bearded toddler. That's probably the most likely explanation.