With cartomizers, where the two are built into one unit, the heating coil can definitely burn the batting. From what I've read here it seems to be less of an issue with the traditional two-piece atomizer/cartridge setup. The solution to prevent this issue (with cartomizers) is to keep the batting material wet with
e-liquid, and stop using the carto when vapor production drops off. Once the cart is re-filled or topped off, it should be okay to use again. As a precaution, if I do get the "burnt taste," I don't suck it into my lungs (I always draw into the mouth then inhale with my e-cig).
Someone with more experience then me will drop by soon, I'm anxiously awaiting my first 910 atty and carts in the mail.

I've been using cartomizers for about a month or so now.
Edit: highping is one of those more experienced users I mentioned above. Gotta love an active forum!