Charlie will eat random things in order to not starve yes?
Normally he's in a place where thankfully he's got a regular supply of food while living with Tikki and/or Laika, so he's not usually in a situation that dire to where he HAS to eat non-foodstuffs. While he CAN eat a lot of stuff a human probably shouldn't and still be okay, he definitely prefers stuff that's intended to be eaten since it tastes better. I think the only time he'd willingly eat a random object while living with one of those two would be if someone challenged him to do it, or he was just REALLY that curious about how it would taste.
I think the only time he's really had to fend for himself was in the beginning months of cryptids au- in which case yes, he went through trash cans for scraps, or stole food if he was feeling brave or desperate enough to break in somewhere. In a real pinch, during times where he had to lay low in the woods and avoid going near town, he'd eat rocks- definitely not for their flavor, but because they'd take a while for his stomach to melt and would keep hunger at bay for longer than most other things (and let's be real, he sucked at hunting. Him being a softie about killing cute innocent animals aside, the wildlife could see his fog lamp eyes from yards away. Heck, even if they couldn't, his lanky ass crashing through the foliage would be a pretty good tip off that they should probably book it.)