"[7] Music critic Bart Testa found it ironic that this Doors song was extolling "The Dock of the Bay", which for Redding was a place of defeat and "where he wasted time having found the struggle for life useless", when earlier Doors songs such as "The End" and "When the Music's Over" call vehemently for revolution.

[8] The Doors execution with the song, was to feature elements from R&B[1] and contributions by bluegrass musicians;[1][3] including Jesse McReynolds on the mandolin.

[1][3] The song begins with a fiddle played by Jimmy Buchanan and builds to a refrain which Testa compares to "Touch Me", the Doors earlier hit from The Soft Parade.

[2] Cash Box described it as "smooth, adaptable for dance-minded teens, and even more commercially potent than" the Doors' recent singles, and incorporating a touch of country music.

[13] Chris Ingalls of PopMatters overviewing the 50th Anniversary edition of The Soft Parade, declared "Runnin' Blue" as one of the "oddities" of the album, and deemed its chorus as "cringe-worthy".