There isn't an accepted definition of what looks good; I accept that.
There is, however, a fairly accepted definition of CM. This doesn't enter into it. CM is about expressing your style within certain traditional--and admittedly inorganic--boundaries. Subtle coloring outside the lines demonstrates skill and finesse. SW&D is about artfully working outside rules or at least pushing them to their breaking point.
This thread clearly belongs in SW&D; there are quite a few people there who will probably work the vest-sans-jacket to great effect.
On a related note, here is a picture of me sitting on a toilet:
Edit: Both ACS and Tira walk the boundaries of CM. ACS crosses the boundaries more, but he does it with a sense of fun, takes his lumps when they come, and isn't defensive. In short, he has the personality for it to work (as well the taste, generally--sorry ACS, but I can't get behind that one four sided tie or those jeans )
I like this. I can't see the tie very well, however. Is it knit?