to screen for Nazi spies, because jazz was considered a "degenerate" form of music by the Nazi party. Later during the Nazi regime, bouncers also increasingly barred non-German people (such as foreign workers) from public functions, such as 'German' dances at dance halls. Bouncers also often come into conflict with football hooligans, due to the tendency of groups of hooligans to congregate at pubs and bars before and after games. In the United Kingdom for example, long-running series of feuds between fan groups like The Blades and groups of bouncers in the 1990s were described by researchers. Bouncers have also been known to be associated with criminal gangs, especially in places like Russia, Hong Kong or Japan, where bouncers may often belong to these groups or have to pay the crime syndicates to be able to operate. In Hong Kong, triad-connected reprisal or intimidation attacks against bouncers have been known to occur. Hong Kong also features a somewhat unusual situation where some bouncers are known to work for prostitutes, instead of being their pimps. Hong Kong police have noted that due to the letter of the law, they sometimes had to charge the bouncer for illegally extorting the women when the usually expected dominance situation between the sex worker and her "protector" was in fact reversed. In the 1990s and 2000s, a number of bouncers have written "tell-all" books about their experiences on the door. They indicate that male bouncers are respected by some club-goers as the ultimate 'hard men', while at the same time, these bouncers can also be lightning rods for aggression and macho posturing on the part of obnoxious male customers wanting to prove themselves. Bouncing has also started to attract some academic interest as part of ethnographic studies into violent subcultures. Bouncers were selected as one of the groups studied by several English researchers in the 1990s because their culture was seen as "grounded in violence", as well as because the group had increasingly been "demonised", especially in common liberal discourse (see Research section of this article). 21st century In 2006, a German newspaper reported that organized crime is operating bouncer extortion rackets in "Berlin, Hamburg, the Ruhr Valley and the Rhein-Main region" in which bar owners are "compelled to hire a bouncer, for 100 euros ($128) per hour", to "protect" against damage to their venue from the "wrong" type of patron or violence. In 2008,