[ac29]

> in my experience drug addicts are not very good at hiding it when they lose control.

Addiction takes a lot of forms and its very likely you know people that are good at hiding it.

[Rendello]

I'd spent my childhood around alcoholics and was confident in my ability to see addiction, only to be confronted with someone close to me going off the rails after years of completely hidden amphetamine addiction. Sometimes you really don't know!