Burning trash?

I've gotten pretty interested in the RMH concept. I remember Paul talking about heating for an entire winter just on junk mail. This got me thinking, much plastic and other oil based stuff burns really well. The main concern with burning them is the smoke they release into the atmosphere. But if you're burning extremely efficiently at a very high temperature in a RMH, would they essentially burn "clean?"

I think there's a TON of potential thermal energy stored in hydrocarbons, I make my own campfire starters with petroleum jelly or wax and that adds a crazy amount of burn time and heat to them. Could we harness that for heating as well?

As long as we stay away from chlorinated plastics and are certain that the combustion is clean and complete, this is a low-risk activity. However, there is a considerably chunk of the general population, and (probably more importantly) official departments of Sad Making, that would be aghast that anyone would contemplate doing this. So I tend to talk about it in hypothetical terms most of the time.

Compared to what passes for recycling in most places nowadays, which usually looks like either a short trip to landfill or bulk cargo carriers going to the global South where it gets burned in piles or washed into the ocean, this seems like one of the least bad options. It also means you don't have to rinse out the last bit of yogurt, bacon juice, or Sriracha sauce.

How can you tell if it's chlorinated plastic, and what's the risk with that?