The invention relates to a cleaning agent, characterized in that the cleaning agent comprises a microemulsion or a fluid nanophase system, and has the following components: a) at least one non-water-soluble substance having a solubility in water of less than 4 g per liter; b) at least one amphiphile substance, NP-MCA, that has no tenside structure, does not form structures on its own, has a solubility in water or oil between 4 g and 1000 g per liter, and preferably does not accumulate at the oil-water boundary, with the provision that NP-MCA is not selected from among 2-Ethyl-1,3-Hexanediol, 2-Methyl-2,4-Pentanediol, 2-(n- Butyl)-2-Ethyl-1,3-Propanediol and/or 1,2-Diols; c) at least one anionic, cationic, amphoteric and/or non-ionic tenside; d) water and/or a water-soluble solvent having hydroxyl functionality and, optionally, additives.