The level of 'Spanish' that is known in the US wont be enough to speak in places like Madrid, Andalucia etc. It may be passable in Barcelona, where Catalan is the local language. But Americans are not aware that Castellano is spoken much faster than Hispanoamerican Spanish, so those who think that they 'know' Spanish are surprised to find out that they will need to learn a 'new Spanish' when they move to places like Madrid or Andalucia.