I'm no expert but I'll tell you what I think. The first shot isn't too bad, something I might have taken but I doubt it would have made it to the posting stage. For me it's one of those "looked pretty cool at the time " pics and I have buckets of them. The dog I would have gotten a close up of the face and eliminated the distracting surroundings, either that or a crop. The polka dot piece does nothing for me, I don't know what it is and it doesn't entice me to wonder. The " bishi 300gt" shot looks like maybe you were trying to duplicate a cool product shot you'd seen in a magazine but unfortunately it just comes off as a car bumper. The train has potential, was it shot from a car window? There seems to be motion in the foreground which makes me suspect as much. Don't you just hate wires in your shots? Anyway, hope I'm not too harsh, just the way I see it.
The shoe almost makes sense now I know what it is ( I'm slow sometimes though...Other people are thinking "What's up with this guy, It's a red polka dot shoe...How could he miss that?" I think I may have given the image slightly more visual information that would cue people like me into the fact I was looking at a shoe. They are pretty cool shoes
Knowing now it was a DOF test I can say that you seem to be getting the gist of it.
Anything that gets the bucket out from behind the dog would help IMO. I was thinking you could have moved the bucket before you took the shot but I have the feeling the dog would have moved.