To socialize a bird to bathing at this late date could result in a bird that is resistant to what you are attempting to teach it. With the proper approach many parrots that hate the bath can be encouraged to accept what its ancestors simply took for granted. Patience is a virtue, and teaching an older parrot to bathe will surely make you more virtuous. Patience, patience, and more patience are the necessary tools involved in this process. Your approach in this situation will decide if you are to be successful.
Parrots are very suspicious creatures simply by their nature.
They are preyed upon by other animals, which is a difficult concept for us to comprehend since we are predators with forward-facing eyes. To understand the nature of parrots it is best to simply observe them and try not to dismiss their actions as that which does not matter. Rushing a situation onto a parrot can be very detrimental in getting the bird to accept what you are trying to teach it. Slow down and think of your every move. If your bird exhibits fright when water is introduced, perhaps you are moving too quickly.