The beer in the Old Blue Last near Old Street in London is some of the worst I've ever had. And by my lights if your beer is shocking, you're a shocking boozer, however 'iconic' you are.
EDIT:
Here's shite as well:
The Old Queen's Head, Islington. Full of wankers, beer selection shocking and identikit trendy.
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If you could hear, at every jolt, the blood
Come gargling from the froth-corrupted lungs