What kind of random junk do you mean? No strong smells, no sharp corners (molded plastic usually have some, but they are easy to file down) and nothing that can get stuck to the snake or its food then it should be safe enough. Childrens toys, for example, should be pretty safe for the snake and plastic toys are easy to keep clean. I know one guy who has a toy castle in his rat snakes' cage. It looks out of place, but it doesn't bother the snakes.