Only time I'll ever use tobacco is if I don't have enough weed by itself for a spliff and have no choice but to roll. I just don't like the taste and smell of most commercially sold tobacco though. If you use a little tobacco in a joint I don't see it being all that harmful since the nicotine, tar and all that other good stuff involved is in small amounts.

But hey...why ruin such a great tasting plant with cancer leaf?