How do I know if the physical ink absorber pad needs replacing along with resetting the 5B00 error on my Canon MP287?

It's difficult to definitively know if the physical pad needs replacing without disassembling the printer. However, if you've reset the counter multiple times or if you notice any signs of ink leakage around the printer, it's a strong indication that the pad is saturated and replacement might be necessary. For most users, resetting the counter is sufficient as a first step.