I agree on the knit tie thing (as above). However, I really don't know where this SF convention of slanting tie-bars came from. I suspect it is simply a reaction against the GQ promotion of tie bars worn straight, even though this is more traditionally 'correct' and tie bars are actually designed to be worn this way in most cases. A slight angle gives a hint of studied carelessness, but if you do it as much as you are in this picture, then I think you start to move into trying a little too hard territory. But then this is all simply a matter of individual preference.