First, a quick rant; Fantasy Flight Games, why u no make it direct damage? This card (and it's counterpart Painkillers) are incredibly cool thematically; the concept of self-destructive habits is one that breaths even more life into our pseudo role-play of the investigators we build decks for. It legitimately saddens me when I consider that Rita's athletic career might be compromised by the as of yet not understood effects of smoking on the lungs. It brings me great satisfaction when I outfit Roland with a Trench Coat and a Smoking Pipe and complete the gritty noir-detective look.
To be clear, I am not being serious; I know full well that a card game like this, with a million moving pieces, is not going to keep a straight face in the face of all the possible combinations. I've already accepted that this isn't always going to hold up as a grim horror experience, especially when I held off an eldritch god with two Attack Dogs for six rounds, that one time. Still, would have been nice.
Anyway, the review. You consider Smoking Pipe when you're playing a 9 health, 5 sanity investigator. That's it.
Okay, okay, I'll elaborate a bit: Smoking Pipe and Painkillers have one very obvious drawback; being defeated from damage or from horror holds little distinction. While you can assign damage to non-critical systems through these cards, they require that you've got a big difference in your remaining health and remaining sanity in order to have a noticeable effect in your survivability.
You might think that's the reason I'm recommending 9 health, 5 sanity investigators take this card, but that's only half the story. The other half is that the statement "being defeated from damage or from horror holds little distinction" does not hold for these investigators because mental trauma hits much harder and physical trauma hits far slighter. Starting with 8 health or 9 makes little difference; starting with 4 sanity or 5 does, and should be avoided at any cost.