Like any cleaning, if the cloth is dirty it can leave smear marks on your window.
Your HOBOT 2S comes with 1 set of cleaning pads, but it is always a good idea to have some spare. Helping to ensure your windows will end up with the best possible clean by not having to reuse a dirty pad.
Remember, the process is dry pass, them wet pass. Use a different pad for the dry and wet pass. You cannot use a 298 pad on a 2S due to the air leakage detection system.
There is also no dusting pad required due to the greater suction force with the HOBOT 2S.
The pads are machine washable and should be replaced every 6 months.
Price is for a set of 3 cleaning pads.