Shirt Collars - Fused or Unfused?

I would not say always. Though I always get unfused, I can live with a fused collar. Some makers, e.g., Kabbaz, do a very nice fused collar. I can't live with a fused cuff.

how does one tell from looking or feeling whether a collar or cuff is fused vs. unfused?

Definitely stiffer. Not more liable to shrink in my experience. In any case, the collar band is what you have to worry about there, and it is never fused.

If the collar is very stiff, almost like paper/plastic, the it is fused. If you see bubbling (which is one of their biggest problems) then it is fused.

strong preference for unfused here; hate stiff collars

All the neapolitan shirtmakers are fused and very stiff. Watch my italian shirts here; http://www.styleforum.net/showthread...36514&page=119

Fusing doesn't have to be stiff...

All the ready-to-wear Neapolitan shirt factories might make stiff, fused collars, but the Neapolitan bespoke shirtmakers are a different story.

I think every Good shirtmaker not only in Naples will give you options.
I have never been to Naples but I try to accomodate
Freddy Vandecasteele

This shows ignorance. They are different, and they both have their place. It's true that cheap shirts have fused collars, but certainly not all shirts with fused collars are cheap or low quality.

I have both. However the fused ones once they got creased or wrinkled they are almost impossible to fix. Probably I'm wearing cheap ones.

I think a lot of people prefer sewn-in interfacing just because it's rarely used in ready-to-wear shirts. If you want a neat-looking collar, that stays neat, that's easy to keep neat after laundering, etc., stick with fusing. If you want an imperfect look, a little puckering at the seams, etc., or an extremely soft collar, then you should avoid it. But thinking sewn-in interfacing is superior because most people don't use it seems silly to me.