The left-right ideological position of individuals is a key variable in political science, often used to ease the complexities of political preferences into a single dimension. Despite its widespread use, the single-item left-right scale has faced criticism for failing to capture the nuanced perceptions of respondents and for being susceptible to differential item functioning (DIF), where individuals interpret scale points differently across various contexts. This study investigates the comparability of the left-right scale across 30 European countries using the anchoring vignette approach. Data comes from large, nationally representative samples (N=30,000) collected through computer-assisted telephone interviews. Our findings reveal significant variations in the interpretation of the left-right ideological scale. The ordering, the mean placements of the vignettes and the average distance between vignette placements all varied significantly between countries, indicating substantial cross-national differences in the interpretation of ideological positions. The findings suggest that the left-right concept is not perceived in the same way across Europe. Based on these cautionary results we argue that researchers employing a single-item left-right scale to gauge ideological positions in comparative analyses in Europe should consider implementing corrections for measurement invariance or acknowledge the possibility of varying interpretations.