The vocals of Swans frontman Michael Gira are scathing and direct, covering topics of social decay, corruption, rape, and abuse of power.

[6] Gira described Westberg's playing as "a vast, sustaining chordal sound",[2] and the latter's addition to the band helped solidify it as a serious musical venture;[4] previously, Swans had been fueled by "constant bickering, haranguing, and pervasive mean-spiritedness", according to Kane.

[12] The sound of Filth is defined by the band's unusual composition: two bass players, two drummers (both of which have access to miscellaneous percussive items), and one guitarist all accompanied by a series of programmed tape loops.

[2] The lyrics of Filth and its following albums deal with "violence, extreme sex, power, rage, and the margins of human depravity", according to AllMusic's Thom Jurek.

[17] Gira described his vocals as "screaming/testifying",[8] and Jake Cole of Spectrum Culture called them "locked into an endless loop of provocation, filled with unending allusions to violence, rot and rape".

[21][7] It begins with "Stay Here", which instantly conveys the distorted aggression of the album with chaotic, conflicting drumming, lurching basses, and squealing guitar.

[22][18][23] Gira repeatedly shouts commands like "be strong", "resist temptation", and "flex your muscles",[22][7] occasionally inserting a more enigmatic order, like "stick your hand in your eye".

[22] Hannah called the song "leeringly sexual" and "unforgiving in its crude approach",[22] and Joseph Rowan of Drowned in Sound compared it to early Killing Joke.

[21] "Blackout", the third track of Filth, is a slow, crushing song where the guitar strings "are so loose to lower the pitch that they take on a kind of rubber-band twang when plucked", according to Cole.

Heller wrote that the song "doesn’t denigrate the submissive; this isn’t fascist music, as its unforgiving textures might indicate, but a profound inversion of power".

[22] Cole wrote that it "erupts from the mouth of hell itself as clanging instruments tumble slowly down a hill and Gira, the Charon guiding these damned souls, commands his followers to attack an assailant".

The Line of Best Fit's Andrew Hannah called the album "a brilliant work of art" and praised how, despite being from 1983, it still sounded "uncompromising and utterly vital" in 2014 (a sentiment that Alex Biese of Asbury Park Press echoed[31]).

[22] Jason Heller of Pitchfork appreciated the brutality of Filth and noted how it effectively established what Swans would become,[13] and Joseph Rowan of Drowned in Sound highlighted the album as a nearly perfect form of intense, angry music burdened with the downside of becoming exhausting;[21] in a more middling review, AllMusic's Ned Raggett concurred that Filth becomes tiring in its latter moments, but said, "in small doses, though, it's great, and early Swans really is like little else on the planet before or since".

[1] Jake Cole of Spectrum Culture wrote, "the music presented in this collection often sounds like a preemptive parody of Swans’ most extreme moments rather than the first instances of them, but, when it connects, the visceral impact of this fearsome band is evident from the start".

[10] In 2014, John Calvert of Fact wrote, "A milestone in extreme music — a sound heavier, more vicious and more all-out evil-sounding than any metal band had produced by 1983 — with Filth, Swans took the rock form a few gargantuan steps forward".