Depends!
If you work in any service industry such as being a mechanic, building trade, electrics, IT, property management, etc, etc then you can easily work just in English as there are companies purely targeting the ex-pat communities and everyone I know that works as such does very well. Doesn't mean it's the right thing to do but it's definitely an easy step into working in Spain that doesn't involve working in a bar or handing out flyers. There are a huge amount of companies down here that just speak English so although it's obviously an advantage to speak Spanish it doesn't mean you have to
