Sonnendec
If the standard of ATC at Barcelona (I speak as both an ATCO AND Corporate pilot) was up to scratch then dual language would not be a problem. However, it isn't, and they can't cope with it, so shouldn't be doing it. Unreasonable speed control requests, a belief that Vortex wake separation is is purely voluntary, not mandatory. Accent problems that cause real problems in ATC/Pilot comprehension (many of these people would NOT pass ICAO level 4, the minimum required - but I suspect that will be glossed over and they will be awarded it anyway so they keep their jobs).
This is not anti-Spanish, it's not xenophobic. You can fly to Germany, France, Holland, Belgium and feel safe. The same applies when I fly into Malaga - never have a problem there at all, very impressed with ATC. Fly to Barcelona, and the trust in the pilot / ATCO partnership is non existent - they are NOT up to the job.