How do you know.....

Doing some detailing work on the Tundra. The truck had scratches and imperfections, so I used my Orange Foam Correcting Pads Item# 10617. I also have black pads and red pads.

My question is how do you know when it is time to throw the old foam pads out and get new ones? They are a bit stained but still seem to work.

 

What did you mean by "Revitalizer"? I usually use some Tide and since the pads say they are machine washable....I wash them.