Nice, I like how you used a harsh light sourse to illuminate the buts--just very well done. Would have liked a little more DOF, the blur in the foreground kinda distracts from the photo.
7 - Good idea, colors, composition and textures are good. Criticism; perhaps a tighter crop at the bottom, to me the bottom 'butts' that are out of focus dominate the shot, that or different 'focus', because the ash and tobacco at the 'base' adds a good element in my opinion.
I wonder whether this would work a little better with the focus being on the cigarette ends at the bottom of the frame. As it is, my eye seems to wander around without really finding anything to grab my attention.