I was a bit worried there :) the color of trash only indicate where it came from, it has no use expect for the look.
The trash gets more colorful depending on it's value (how much money it gives). But the actual color only depends on where the trash was generated.
There's a lot of people that played the game and you're the first one that commented on the minigame! :) They'll have a more important use in the full version.