Worst book ever to win a Hugo

On Tor.com, Jo Walton continues her highly entertaining series of posts analyzing all the past Hugo winners and nominees. She's just made it to 1955 and They'd Rather Be Right, the "worst book ever to win a Hugo": "The book is generally believed to be so awful that there are conspiracy theories about why it won. Goodness knows what the voters at Clevention in Cleveland in 1955 were thinking. The most sensible suggestion I've heard is Dave Langford's–Clifton had written good short stories, the voters hadn't read the novel and were going on past performance. In which case, oops. It isn't in print. It is barely in the memory of having been in print."