Lyric discussion by velvettt 

Cover art for Cotton lyrics by Mountain Goats, The

i always saw this as a song of disappointment. the first half of the song seems like he's talking about cowards (jumping ship) and selfish (can't and won't feel sorry) people he's known in his life. basically, he's remembering the past, how it's affected him, and the all of the things he's left behind.

and as the person above me stated, "cotton" is a slang term for a small piece of cotton used to draw-up your drug of choice into a syringe.