Giggs' name has been strewn across the tabloids amid allegations he had an eight-year affair with his brother's wife Natasha, with a number of other women also claiming to have slept with the married Welshman.
QPR midfielder Barton, who has had a series off-pitch problems himself and was jailed for assault in 2008, has attacked the media intrusion into player's lives but says there is no excuse for the behaviour of Giggs.
Barton said: "The Giggs issue in any walk of life is not right, the behaviour of the man towards another man, towards his brother. It's not right."
The former Newcastle United and Manchester City midfielder also claimed that there would have been "public executions" had the England football team behaved like their rugby union counterparts at the World Cup.
England's dismal campaign in New Zealand lurched from one controversy to another before and after their quarter-final exit, with players criticised for their off-field behaviour during the tournament.
Outspoken Barton, who has one international cap, said: "If that was an England football team at a World Cup, there would probably have been public executions when they got home. 'Football's a gentleman's game played by thugs', I hear quite a lot, 'and rugby's a thug's game played by gentlemen'.
"The minute a footballer steps out of line, I think the media in this country - because of the sums of money they earn and also because of the stigma attached - are really quick to jump on it."
Barton also took issue with footballers' status as role models. "There is a lot of envy about what footballers earn, the astronomical figures," he said. "That's not our fault. "I went from being on £300 a week playing in a big league to £6,500 a week.
"No-one taught me how to handle that, no-one taught me how to be a man. I didn't instantly get that wage increase and become a role model. I was still the same kid from a working-class council estate."