Our experience with white pepper has been very negative--there is a fetid odor which seems to be present in varying extent in all we have tasted; however, as some chefs, such as Joel Robuchon cook exclusively with it, we are reconsidering, as there are dishes that would look better without black specks.
We spoke a few years ago with a woman who was quite knowledgeable about the subject and explained that the problem is that the peppercorns are soaked in large ponds to remove their outer coverings; the lack of attention to the sanitation of the ponds results in the fetid aroma.
She also said that there are producers who do carefully attend to the ponds, and some soak the peppercorns in running streams to overcome the problem. At the time we were less interested in using this ingredient than we are now, so we did not take note of where we might look to find higher quality white peppercorns.
If anyone has a suggestion for where to look, we would be interested.