It's an academic difference for me too, since I don't smoke either, but the reasons that I consider pot to be a lesser evil are:

1. While pot isn't exactly calcium-enriched orange juice, it's not as unhealthy as tobacco 2. Pot isn't physically addictive 3. Second hand pot smoke smells better than second hand tobacco (there's my shallow side), and isn't routinely inflicted on other people 4. Pot has alternative therapeutic uses, while tobacco has alternative insecticidal uses.

And for the record, I think Sophocleese's guest was hideously rude... and I'd rather smoke than commit adultery.

Cheers, Marion