Burning plastic

I've been thinking this over and I don't think my concern about not burning plastic is ecological but just general good housekeeping. I was raised by the Girl Scouts: You leave a campsite cleaner than you found it.

Plastic and aluminum foil do not burn completely, so instead of leaving a pristine fire pit for the next traveler, you left bits of junk. I've come across fire pits that were used as garbage pits.

As responses slow down, I want to thank everyone for offering such thoughtful and considered responses. It has been useful to read so many perspectives and reconsider my own. While there have been many different opinions and practices presented, including some that contradict my own, I would be honored to trip with everyone here.