In the days when Iberia still had pretensions of offering service, I used to fly longhaul F and C a lot, often with a colleague whose English surname, when pronounced the Spanish way, sounded like a Spanish swearword. Cabin crew usually found some embarrassment in using his surname to address him, and ended up calling him 'Senyor Martin', which was his first name.
Also reminds me of a Spanish friend called Juan Carlos, which is often abbreviated in conversation to Juanca ....... which if you pronounce it in Spanish sounds rude to English ears ... you can't win!