A system for maintaining calender rolls of a paper machine clean when producing high-gloss paper or coated paper, such as LWC or MWC. To prevent a coating agent, such as coating dye, from adhering onto and soiling a smooth surface of a calender roll, with an overheating phenomenon, the system has a second measurement station (10) provided with measuring and indicator means for producing an output indicating soiledness of the web (W) or a humidity profile. When the output of the second measurement station (10) indicates excessive soiledness or an uneven humidity profile, the system performs at least one of: cleaning the surface of the smooth-surfaced calender roll; changing the nip load in the calender (5); making a correction adjustment of the CD-directional humidity profile of the web (W); cutting the web (W) and conducting it into the pulper; and/or changing the running speed of the web (W).