What Jay says about the ability to see discoloration caused by moisture/fungus is not to be taken lightly.
I was examining a bad 'ding' on my painted bowsprit where one of my anchors banged an edge exposing the wood. I was trying to decide what to do about it when I noticed what I thought was maybe a 'stress crack' in the paint on top of the bowsprit. On closer examination I discovered it felt a bit soft underneath. I get an ice pick and discover mushy wood about 8-10" long and an inch or two deep right down the middle. Otherwise unless you looked real close, visually to the casual eye it was non-existent.
Had the bowsprit been clear/varnished I'm sure I would have noticed it early on and saved myself from having to replace the whole thing.
That said, I do like the combo of a white bowsprit among all the teak. My new one is again painted white (2 part polyurethane) but I've taken the precaution of thoroughly 'soaking' the new wood with 3 coats of penetrating epoxy (including any holes that were drilled) before painting and carefully rebedding everything with either butyl tape or Sikaflex.