Arabic-Spanish simultaneous interpreting (AR-SP SI) in Spain and the Arab world is, on the whole, carried out by native Arabic speakers. Specifically, 87.5% of AR-SP SI interpreters in Spain have Arabic as A language and Spanish as language B. Given this peculiarity, for this linguistic combination it was interesting, as well as novel, to analyse users' assessment of AR-SP retour quality and its acceptability, by studying three quality criterion, two relating to content - the fidelity and accuracy in the delivery of the source speech - and one relating to form - the non-native accent of the interpreter (NNAI) in Spanish. To this end, this mixed quantitative and qualitative study sounded out the opinion of 50 users by filling out a questionnaire. After watching a 30-minute conference video interpreted by a native Arabic interpreter, subjects completed 6 mixed close-ended and open-ended questions related to the three aforementioned criterions. The results show that the wide majority of users evaluated the source speech delivery as good comprehension of the content, and that NNAI did not seem to have a negative impact on their overall evaluation.