He's an 8-year-old beagle. I am his secondary owner of 6 months - his primary owner has owned him since puppyhood. Apparently there have been failed attempts to give him some basic training in the past, most notably enrollment in doggy discipline school. (They gave a refund and expressed that he was not welcome back after the first day of training.)
I have started to read up on books and resources for training dogs as I feel he does need some basic training and I have come to understand that he has been unwittingly trained to lunge at garbage, put it in his mouth and swallow it as quickly as possible. He eats other animals' poop, any and all food he finds on the ground, sticks his snout into garbage and plastic bags at the slightest opportunity.
He has had very little training and little if any understanding of command words. I want to get started right away on correcting the garbage eating behavior as I am concerned he will eventually eat something that does something horrible to him. It is difficult to avoid garbage on the ground as we live in a city area that is extremely littered. (Even the parks have food garbage lying around from picnics.) I don't want to stop taking him on walks while I study basic training principles and canine communication - we are currently living in an apartment building and he has the run of the veranda, but that's not enough space for him is it?
Is it possible to start training him to stop eating everything he can reach in these circumstances? How might I go about it?