I really dont consider Waters to be a junkie.... and I don't consider Comfrtably Numb to be a song about heroin.... that is Nobody home ("I have a silver spoon on a chain".... what that tells you???) wich is a song talking about the life of a rock star, with many drugs adicction...

I can't recall the source nor the concert itself, but I think it was during the In the flesh(animals) tour that Waters had neumonia or something like that, and he couldn't even move, so they doped him and sent him to the stage "I went to a concert when I could hardly stand on my feet" I recall him saying.... VERY similar to what happens in comofrably numb (let's not forget that apart of talking about different issues, The Wall tells us a story)

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"And if the band you're in starts playing diferent tunes, I'll see you on the Dark Side of the Moon"