Is it true that un-dissociated HCl exists in dilute hydrochloric acid?

My book says that the equilibrium constant for $\ce{HCl + H\_2O}$ is so high that the reaction goes to completion. But that does not make sense since the existence of an equilibrium constant for this reaction means that there is some reactant in the equilibrium mixture. I think there is only a very small amount of reactants in the mixture. What is the truth?


