The cultural diversity of users of technology challenges our methods for usability evaluation. In this paper we report on a multi-site, cross-cultural grounded theory field study of think aloud testing in seven companies in three countries (Denmark, China and India). The theoretical model that emerges from the data suggests that the production of a usability problem list is multi-causal and subject to cultural variations. Even the way usability problems are experienced by test participants may be different. In the discussion we outline practical guidelines for a test that is more sensitive towards cultural usability.