The construction of daily electricity consumption profiles is a common practice for user characterization and segmentation tasks. As in any data analysis project, to obtain these load profiles, a stage of data preparation is necessary. This article explores to what extent does the selection of the data preparation technique impacts load profiling. The techniques discussed are used in the following tasks: standardization, construction of data, dimensionality reduction and data enrichment. The analysis reveals a great incidence of the data preparation on the result. The need to make the data preparation process explicit in each report is identified. In particular, it is highlighted that the most usual default standardization process, column standardization, is not adequate in the preparation of energy consumption profiles.