Barton was talking to talkSPORT after criticism from Jose Mourinho of United's fans.
He said: "Old Trafford is tourist-central, but most of the grounds are now.
“You've got what Roy Keane called the 'prawn sandwich brigade' who were at Old Trafford and all the tourists but, to be fair to Man United, whenever I've seen them play away I'd say they've got probably the best travelling away support or as good away support as anyone in the country.
“Liverpool fans sing 'You'll Never Walk Alone' at the start of the game, and that's pretty much it.
“I'm telling you! Unless they score or it's one of those European nights.
“Who are brilliant at home? I think of teams like Crystal Palace and the other smaller stadiums.
“I think once you start making massive stadiums the atmosphere suffers."