Use of one or more polycarbonate-, polyurethane- and/or polyureapolyorganosiloxane compound(s) containing at least one structural element of the formula: -Y-A-(C=O)-A-, each A being independently selected from S, O and NR 1, Y being selected from di- to polyvalent, in particular tetravalent, straightchain, cyclic or branched, saturated, unsaturated or aromatic, substituted or unsubstituted hydrocarbon residues with up to 1000 carbon atoms (the carbon atoms of an optionally present polyorganosiloxane unit not being included in said number), which may contain one or more groups selected from -O-, - -, -NH-, -NR 2 -, -(N + R 2 R 3)- and a polyorganosiloxane unit with 2 to 1000 silicon atoms, R 1 being hydrogen or a straight-chain, cyclic or branched, saturated, unsaturated or aromatic hydrocarbon residue with up to 40 carbon atoms, which may contain one or more groups selected from -O-, - -, -NH- and -NR 2 -, R 2 being a straight-chain, cyclic or branched, saturated, unsaturated or aromatic hydrocarbon residue with up to 40 carbon atoms, which may contain one or more groups selected from -O-, - - and -NH, R 3 being a straight-chain, cyclic or branched, saturated, unsaturated or aromatic hydrocarbon residue with up to 100 carbon atoms, which may contain one or more groups selected from -O-, - - and -NH-, or being a divalent residue which forms cyclic structures within the residue Y, or one or both of the residues A adjacent to Y may form a nitrogenous heterocyclic residue with the residue Y located between them, and in the entire compound all the residues A or Y or R 1 or R 2 or R 3 stated in formula not necessarily being identical, providing that, in the entire compound, at least one of the residues Y comprises a polyorganosiloxane unit with 2 to 1000 silicon atoms, or the acid addition compounds and/or salts thereof, for treating a hard surface, the treated surface being protected from soiling and/or the detachment of soiling from the surface being facilitated, and/or for improving the cleaning performance of a cleaning agent for a hard surface. Y being selected from di- to polyvalent, in particular tetravalent, straightchain, cyclic or branched, saturated, unsaturated or aromatic, substituted or unsubstituted hydrocarbon residues with up to 1000 carbon atoms (the carbon atoms of an optionally present polyorganosiloxane unit not being included in said number), which may contain one or more groups selected from -O-, - -, -NH-, -NR 2 -, -(N + R 2 R 3)- and a polyorganosiloxane unit with 2 to 1000 silicon atoms, R 1 being hydrogen or a straight-chain, cyclic or branched, saturated, unsaturated or aromatic hydrocarbon residue with up to 40 carbon atoms, which may contain one or more groups selected from -O-, - -, -NH- and -NR 2 -, R 2 being a straight-chain, cyclic or branched, saturated, unsaturated or aromatic hydrocarbon residue with up to 40 carbon atoms, which may contain one or more groups selected from -O-, - - and -NH, R 3 being a straight-chain, cyclic or branched, saturated, unsaturated or aromatic hydrocarbon residue with up to 100 carbon atoms, which may contain one or more groups selected from -O-, - - and -NH-, or being a divalent residue which forms cyclic structures within the residue Y,