I have also read that tobacco is toxic to cannabis and therefore I do not recommend anyone to use it.It even said to not even touch your plants if you smoke cigs before you wash your hands.I will try and see if I can find the article on it,but it was a few years back so it might take awhile.Until someone finds a written article on it lets all cool down or I will suggest that the thread be closed temporarily.
Tobacco in its burnt form is (a lot more) toxic. Most chemicals and other things that get burned normally become more toxic or toxic. Highly doubt tobacco juice is "toxic" to plants as many have used it successfully without any real issues, even i have.
What you might be referring to is tobacco smoke, it is indeed toxic to cannabis plants and most plants in general. I remember a while ago when i was smoking a cig and blew some of the smoke into a few tomato cuttings, the next day 3/4 of the cuttings turned black and started rotting (all within 24 hours!!).

