Designers and Typos

How does this happen? You design a sign for a client and neither you nor the client realize a word is spelled wrong. Ok so maybe anyone can mix up “Physic” and “Psychic” but still, someone should have noticed this along the line. It is a fairly simple sign – not much writing to have to use ‘spell check’. I saw this at the state fair — and there wasn’t just 1 sign there were 4. FOUR SIGNS. How could neither the designer or client notice this? Boggles my mind.