Abstract: A device and a method are disclosed for checking properties of wares and services. Standardized properties of wares and services are stored in a first database, wherein the wares and services are provided with a unique product identification code. Exclusion and desired criteria for wares and services for at least one user each are stored in a second database, access to the criteria being given by a unique user identification. With aid of a device which determines the product identification code, the product properties are preferably retrieved on-line and compared with the criteria of the user. The comparison can be done on-line on a central server or on a hand-reading device which the user carries with him. The user is advised optically or acoustically of the result.