Thank you everyone for your responses so far, and please keep them coming.
When I started this thread my intention was not to create a list of most loathed shapes, but to highlight the fact that for every shape existing, there will be someone who will love it, even if there are a lot of nay-sayers.
For example, I love bulldogs, but not necessarily Rhodesians. I have fairly strict criteria which bulldogs I buy - I dislike tall bulldogs, or ones with elongated shanks/stems. Bulldogs (the canines) are meant to have over-sized heads, and short and squat, compact bodies. Anything else will not meet Cruft's standards. So I choose my bulldogs (the pipes) accordingly.
To my eye there is something inherently wrong with Castello's prognathistic Shape 55. But it has lots of fans and even a dedicated thread or two on these Forums.
Vive la difference !