Question: What band's musically "dirty" sound was a forerunner for the later grunge bands to come out of Seattle, The U-Men or Hayden?

Context articles: List of grunge bass players
Frosting on the Beater
Black Rabbits
List of American grunge bands
Hayden (musician)
The U-Men
10 Minute Warning
Tad (band)
Grunge
Mark Arm

This list of grunge bass players contains notable performers on electric bass who play (or formerly played) in well-known grunge bands from the Seattle area, other parts of the US and Australia.
Frosting on the Beater is the third album by the Seattle rock group The Posies, released in 1993.
 It featured a heavier, more intense sound than the band's prior works, in part due to production duties being handled by Don Fleming.
 "Dream All Day," "Solar Sister" and "Definite Door" were released as singles, with the first two getting moderate airplay and the third being the band's only single to break the UK Top 75.
 "Flavor of the Month" was a swipe at the many overnight-sensation grunge bands in The Posies' hometown of Seattle.
 "Coming Right Along" appeared on the soundtrack to the movie "The Basketball Diaries" (1995, Island Records).
 "Dream All Day" was later used as the title of the band's best-of compilation, released in 2000.
 Frosting On The Beater was the last album original drummer Mike Musburger appeared on.
Black Rabbits is the seventh studio album by Australian post-grunge band Grinspoon, which was released on 28 September 2012.
 Its title is Cockney rhyming slang for "bad habits", which relates to their reputation as being "a hard rocking, harder living band from Lismore, NSW, who emerged at the turn of the millennium with the same never-say-no ethic of Seattle's toughest grunge bands."
This is a list of American grunge bands.
 It includes rock bands and solo artists formed in the USA whose primary genre is grunge or either they have or had the elements of it in their music style.
 Grunge music is a subgenre of alternative rock that emerged during the mid-1980s in the American state of Washington, particularly in the Seattle area.
 Inspired by hardcore punk, heavy metal, and indie rock, grunge is generally characterized by heavily distorted electric guitars, contrasting song dynamics, and apathetic or angst-filled lyrics.
 The grunge aesthetic is stripped-down compared to other forms of rock music, and many grunge musicians were noted for their unkempt appearances and rejection of theatrics.
Paul Hayden Desser (born February 12, 1971) who records as Hayden, is a Canadian singer-songwriter from Thornhill, Ontario.
The U-Men was an American rock band, formed in Seattle, Washington, in 1981 and active until 1989.
 They toured extensively across the United States.
 Their musically "dirty" sound was a forerunner for the later grunge bands to come out of Seattle.
10 Minute Warning (also known as Ten Minute Warning) was a hardcore punk band from Seattle, Washington.
 They became famous locally as one of the first bands to adapt the popular punk sound to something slower and heavier, paving the way for grunge bands like Green River and Mother Love Bone before breaking up in 1984.
Tad (often styled as TAD) was an American grunge band from Seattle, Washington, formed in 1988 by Tad Doyle.
 Among the first of the many bands which came out of Seattle in the grunge era, Tad was notable for the fact that its music was inspired far more by 1970s metal (much like Alice in Chains and Soundgarden) than the punk which influenced many other grunge bands.
 Although their commercial success was limited, their music is still highly regarded amongst grunge fans.
Grunge (sometimes referred to as the Seattle sound) is a subgenre of alternative rock and a subculture that emerged during the mid-1980s in the Pacific Northwest U.S. state of Washington, particularly in Seattle and nearby towns.
 The early grunge movement revolved around Seattle's independent record label Sub Pop and that region's underground music scene.
 By the early 1990s its popularity had spread, with grunge bands appearing in California, then emerging in other parts of the United States and in Australia, building strong followings and signing major record deals.
Mark Arm (born Mark Thomas McLaughlin, February 21, 1962) is the vocalist for the grunge band Mudhoney.
 His former group, Green River, is one of the first grunge bands, along with Malfunkshun, Soundgarden, Skin Yard, the U-Men, and others.
 He is also the manager of the Sub Pop warehouse and previously worked at Fantagraphics Books.