The album is experimental in its use of electronics and sound and marks a stark departure in Sylvian's musical career, moving in an ambient direction and featuring fewer occurrences of melody.

[1] During his later days on the label, Sylvian was seen as "a historical oddity" on their roster as opposed to "a sound business investment," seeing as he had a developed cult following but had very limited commercial success.

[2] Although the musician was preparing compilation albums of his work for Virgin, he found it a creatively stifling process, but despite wishing to "start over again" had no support from the label.

[4] Sylvian used Blemish to channel his emotions "as a kind of creative catharsis", in the words of Flux magazine, using his unhappiness to "delve deeper into some of the darker corners of his consciousness.

"[5] Sylvian said that he had a "sense of trauma" that needed addressing and "wanted out," adding: "I used the emotions to punch further into the darker recesses of my own mind, to see how far I could go, to see what I would find there and if and how I could give it voice.

It's an odd one to talk about, because obviously I was going through a break up of a marriage and that was very painful, but as I got into the studio and shut the door I would allow myself into the darkest recesses of my heart and my mind to uncover what was there.

"[5] Reviewer Chris Jones felt Sylvian's "singular extemporised recording processed" freed him from "any previous sense of precious perfectionism".

[10] Sylvian had decided he had taken the form of pop songs to their pinnacle with his previous album, Dead Bees on a Cake (1999), and when beginning work on Blemish, he had the desire "to eradicate the past and to find a whole new vocabulary for myself.

"[3] In addition to the new sonic experimentation on the album, Sylvian's voice, while retaining his signature vibrato reminiscent of Bryan Ferry,[1] was closely microphoned, and his harmonies were intimately double tracked.

"[8] Written about his divorce with Chavez, Sylvian's lyrics on Blemish are more honest and emotionally open and less oblique than on previous albums,[4][1] despite "numerous disfigurations of clear-cut linear thought," according to critic Andy Kellman.

"[4] Nonetheless, Dave Gavan of The Quietus considers Blemish to be "a surprisingly recrimination-free affair as divorce albums go," highlighting the lines "The trouble is / It's impossible to know / Who's right and who's wrong" from the title track.

While Sylvian denies any pathological forgiveness to the "even-handedness" of the lyric, he nonetheless conceded that "it's possible to see through the anger and know that the degree of hurt you're experiencing is colouring everything.

Distinctive fluctuations of a tube amp, vibrato set to medium speed and high intensity, introduce us into the room space and its atmosphere.

[13] Most of the songs are based around a single chord, although according to Jones, the material avoids becoming drone music due to the close attention "being repaid by a swarm of insectoid-glitches".

[1] According to biographer Martin Power, the music is often little more than "an echoing guitar chord or spare keyboard flourish,"[2] while reviewer Nick Southall says the melodies "are pulled apart so slowly and deliberately that you can see the joints and mechanisms of pop music, the purposeful analogue crackle becomes a dovetail for a small song made long, the dry, dawdling dramatics of his voice, at once ancient and modern, become a cog-wheel for a pop-opera soliloquy.

"[16] While clues concerning the album's troublesome background are apparent throughout Blemish, Andy Kellman of AllMusic said the messages being obscured by "meticulously organized sounds," like handclaps, rattling shopping trolleys and fragments of Bailey's delicate guitar work, as well as Sylvian's non-linear lyrics.

[15] On "The Only Daughter", Sylvian's vocals are chopped and snipped on several lines, while the song's ambience is cut by a quiet crackle and background tones.

[2] The oscillating "The Heart Knows Better", containing a relatively simplistic message of redemption,[1] features a shuddering, struck open guitar chord and slow vibrato.

[15] "She Is Not" features Bailey's guitar, while "Late Night Shopping" contains "mantra-like intonations," which, according to Jones, reinforce the sense of agoraphobia which emerges with the lyric "We can take the car.

"[9][11] Featuring Fennesz's arrangement, the song consists of "twisted fragments" with a melody barely surfacing, while Sylvian sings of his "search to reach the sunshine that awaits him above grey skies".

[16] In late 2003, Sylvian embarked on the A Fire in the Forest tour in promotion of Blemish, playing in the United Kingdom, Italy, France, Germany and the Netherlands with a band line-up of Steve Jansen and Masatksu Takagi, using only keyboards, laptop computers and a single guitar.

[3] He also felt the remix album helped explore the "emotional core or aspects" of the original songs on Blemish and place them into new contexts in order to see "how they resonated".

[21] Magnet wrote how Sylvian became grander when "[f]aced with conventional, if not threadbare, tunes," describing Blemish as "the subtlest opera of tweaked, quaking noises".

[19] Andy Kellman of AllMusic called Blemish a "work of beautiful, desolate fragility," and "an unforeseen detour taken by David Sylvian, who has made eight of his most bare, anguished, and intense songs, all of which are neither pleasant nor the least bit settling.

[14] Craig Rosberry of Billboard felt that "although several entries tread a thin line between self-analysis and self-indulgence, the standouts brilliantly convey the album's pervasive themes of fractured relationships, emotional turmoil, redemption, truth and spiritual enlightenment.

[22] Sylvian felt the lack of lyrical conceit on Blemish was key to its success, calling it his most "unguarded" work, "minimal in design".

[5] Jess Harvell of Pitchfork reflected upon Blemish as a "small masterpiece,"[23] while Chris Dahlen of the same website later said it "may be the most powerful album he's ever recorded, the rare case where an artist uses his maturity to show more pain than he had in his youth.