Australian and Italian Oktoberfest revellers have been accused of over-sexualising the annual event and using it as a chance to wear "porno dresses", MailOnline Travel reports.
A Munich-based crime author asked why so many people felt the need to poorly imitate the traditional Bavarian clothing.
In a newspaper interview this week, he said: "With the young women it often looks like porno dresses, short and low-cut and cheap material.
"It has nothing to do with identity."
The number of people wearing traditional Bavarian outfits at the world's most popular beer festival, which starts on September 22, has surged over the past 10 years.
Franz Thalhammer, 70, a former chairman of Munich's Georgenstoana Baierbrunn folk group, said it was a shame that costumes were being denigrated.
He said: "A dirndl is something nice, it can make almost anyone pretty. But some of the dresses you see these days are crazy.
"You go in a tent and it's full of paralytic Australians and Italians and they've forked out €250 [$445] for a complete Bavarian outfit and think they're Bavarians. It's as if I'd walk around half-naked and say I'm Australian."
British fancy dress shops said that customers now want "sexier" items as opposed to the traditional outfits.
Ulku Stephanides, who has run the Carnival Store in Kensington, west London, said: "For women, we have either knee-length or shorter than knee-length dresses. People used to have a normal size. Now, because models are wearing these costumes, the girls come to the shop and they say: 'I want to look sexy'."
Ms Stephanides, 55, said while locals preferred knee-length, skirts, the cut of dress around the cleavage was more exposed.
She said: "They have their boobs out."
Although that trend was not confined to Germany, as she told The Times her British customers also wanted to express themselves.
Ms Stephanides added: "That's the new generation. Last week I was serving one girl; she was like the Queen of Sheba. She was buying a costume for £20 and taking photographs to show friends on Instagram. She said: 'I don't look sexy enough. I have to go to Germany, to Oktoberfest'."
Around 6.2 million people attended Oktoberfest last year, where 7.5 million one litre glasses of beer were drunk. Britons were among the top ten visitors to the annual festival, which has been running since the 1800s in.