Meat by products in raw feeding

I alternate feeding my cats between raw and canned, as I know raw is the best for them. But I keep reading on this forum and others to avoid canned food that contain meat by products. I did contact two manufacturers of raw meat that I buy, and I was told that the whole carcass is processed. That will imply using meat by products. So if that is the way it is done in raw, ( at least with these two, don't know about everybody else) why should it be bad in canned food ?

You'll have to be more specific. Does the canned food list meat by products on the ingredients? What brands are we talking about? 

If it says meat by products on the can then yes.

Take Fancy feast Classic or Pate in Canada. I heard good things about it, and no carbs. But it says meat by products  on every flavor without giving details of what that is, and everybody says to avoid meat by products. Well the brands of raw I'm feeding ( Tollden farms and Carnivora ) use the whole carcass. My understanding is that there are meat by products if that is the case. So either meat by products is no big deal or I'm missing the point here.