My dad actually asked if I could brew him some Watney's Red Barrel, apparently he loved it back in the day... Saying that his other fave was Newcastle Brown Ale, until he tried a bottle recently and discovered that they made it even nastier. lol
I said I'd try to brew him a decent brown ale instead. lol
The worst I have ever had (ignoring cans of John Smiths and Boddingtons creamflow), was pints of Toby bitter in a pub in Greenwich! It was keg not cask, and as fizzy as a can of pop! Coming from the midlands the idea of a fizzy bitter was utterly bizarre too me... I've since had some of the Meantime ones in another pub down there whilst visiting with my wife and they were quite nice, even though still fizzy....
Must admit, there are still some rather lousy commercial brews being sold. I will never, ever bloody ever touch a pint of stone's bitter ever again from a pub. Worthy's eww. Most lager's nope. There's even been some real ales I've had in the past couple of years where the barmaid has missold me it. I've had a couple of gulps and stood up immediately and thought, 'right, next pub please' lol