No Revenue on Some Purchased Items

They don't generate revenue themselves but do add to the multiplier score to increase the revenue you do earn on your revenue generating buildings.

Wow. I have no idea what that means. Maybe that it accrues to a certain value at some specific time--hopefully more than once...? Nevermind, no need to explain it further, I'll just take your word for it. Attempting to try to understand the above concept would take the fun out of this game for me, as I would be trying too hard to keep track of the way it earns $. Whatever it does, it can't be anything significant if it's not even noticeable. I stashed the pile of burning rubber in my inventory long ago, it was so big and unsightly, which I figured would stop it from generating any $ while in there. And yet there didn't seem to be a difference or a drop in earnings when it was gone. I am curious if anybody else has noticed their burning pile of tires (or their chicken coop) giving anything back, however.

Anyway, thanks for the help.