James, Give the bottled Black Rock Stout another try; maybe from another offie that goes through it quicker.
The very first bottle I had of Black Rock Stout at the Salthouse in Galway is one of my happiest beery memories in Ireland. (Galway on a hot sunny day is almost impossible to beat, as is fresh bottled Black Rock Stout; together they're even better.) <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt="

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This is literally the first complaint I've ever heard about Black Rock stout; definitely give it another go.
(Apart from my own complaint that the bottle caps might be rusty months ago because the bottles are capped on foam and when a little bit of stout dries under the cap it looks sort of like rust when you open the bottle. -Oops! My bad!)
Adam