They reflect their location. There's one in Highgate that's really quite nice - not great, but perfectly ok, and the beer's cheap...especially for Highgate.
This thread reminds me of the worst pub I ever went into - in New Zealand. Taken there by a friend for a quick drink, we were the only 'pakehas' in there - the rest of the clientelle all Maori or Polynesian Islanders, male, getting steadily, sullenly drunk. What really shocked me was that there was no seating of any description, or indeed any pretence at all that this was anything other than a place to get drunk. Elbow-height formica tables, strip lighting above, beer at the bar - that was it. A more soulless place on this earth I've yet to see...