There's an old but rediscovered thread discussing how to nicely let a brewer know that his beer sucks. As a BJCP judge and one of the elders in our club, I provide honest but gentle feedback myself.
But there's room to have a little fun with it. Most brewers have a great sense of humor and...
Our homebrew club had an "Iron Brewer" competition where the secret ingredient was vanilla. Bourbon Vanilla Porter took the gold. Great combination of flavors.