This is my guess... if you attach cannabis to cannabis you will have flavor mixing.... attach a tomato branch to your plant you will just get a tomato.
The tomato branch will use the cannabis plant as a host. The genetic compounds are much too different for cannabis traits to be passed on.

Like I said, its just a guess I haven't seen enough results or had a chance to test my theories.

And when grafting, I skip the humidity bag and the v-cut and just take a square cut branch and some duct tape, bandaid it up and wait a couple days in my dwc. after a week i remove the tape and "whammo" no problems. But of course youll want branches of very similar diameter and size. It really is just a vein.