Teach the dog the "leave it" command.
Put toys around your apt. Also, along with the toys scattered around, place objects that are forbidden such as house shoes, children's toys, food objects (a piece of bread, cracker, cookie).
Take the dog on lead around the house. If he sniffs and picks up one of the "approved" toys, reward him with a "GOOD DOG" and perhaps a small treat or the toy itself. Play with him for a few (30 seconds) or so, and then ask him to "drop" the toy. If he drops, PRAISE and REWARD with a treat. If not, gently remove the item from his mouth, say "good drop" and give the toy back to him and try again.
Then walk around the room some more going past the "forbidden" objects. If he stops to sniff and starts to grab the object in his mouth, make an "ACK!!" sound (to get his attention back to you) and say "Leave it" and redirect the dog's attention to a treat (something really tasty). If he leaves the object, PRAISE AND REWARD BIG TIME! He's really done well.
You can also interchange the "drop" command for the "leave it" command for these situations outside. If the drop works better, then use it. The object of the training is to get the dog NOT to eat what he's not supposed to eat from the street.
Continue this with many different objects until the dog is consistent inside. Then transfer the "leave it" command outside when you go out for your business.
I know this is especially important in NYC (having raised Maggie there) with all the junk food, chicken bones and other such mess around everywhere. So, be patient and work indoors until the dog is reliable, then transfer the command outside. It takes time, but soon the dog will learn and you won't have any more problems.
I also suggest getting a copy of "The Culture Clash" by Jean Donaldson and "The Dog Listener" by Jan Fennell. I know I've recommended these books before and I am AGAIN recommending them because they will give you all the help you need in working these commands and the others you will need such as "heel" and "recall" and so forth. Go get these books ASAP and you'll be in a much better position I guarantee you, for when you do get the dog into obedience classes and for all those times when you are going to want to play off leash in the parks!!
Good luck.