We were staying nearby and the family were having a siesta at the hotel. I wanted to visit some old sherry bars and this fell pretty high on everyone's list. Wary of the reviews advising of grumpy bartenders I ventured in.
I had a great hour!
I tried 3 or 4 fantastic sherries, each accompanied by some great nibbles. The gent keeping the bar that day could not have been more friendly, chatting to customers and recommending what to try.
Would definitely return whenever next in Madrid.