Any Walkabout but particularly the one in Shepherds Bush.
Never really frequented any really bad pubs because you can usually see them a mile away. Like in Hull, there was Hull Cheese which had blood trails between it and whatever the hell that one on chapel st was called. Never once set foot in either because I knew there was a beating waiting on the other side of the door.
Edit – Wait, no. I went to a bar in the states called The Surf in Washington state. I was sat in the wrong place, had the wrong accent and was with the wrong people (my father-in-law had declined an offer of a threesome on behalf of his good lady and himself a week or two before). I ended up drinking everyones drinks so we could get out quickly.