Sure, it can be scanned, it’s used a lot in vintage automotive engines when original parts are no longer made, but you would get a better, more accurate result on a watch case with other means. Lots of people think 3D scanning is like an electron microscope - it’s not like that.
I still think it is the way to go for reverse engineering, you can achieve excellent accuracy and the 3D model you have from scanning is perfect for reproduction/clone part for a true 1:1 part.
3D scanning is developing very quickly, trust me I know what I am speaking about. We are speaking about microns in terms of accuracy, I use it for automotive parts, casted and machined.
As for the issue of the metal parts, reflections, you use spray to reduce this as minimum as possible as a potential problem. There are handheld devices this days that are helpful to scan it quickly and to scan some positions that are difficult to reach. Pairing with the classic CMM and you can really obtain whatever you want. Finally, pair this 3D models with high accuracy CNC machines and you have a great result. Probably if all this "ingredients" were in the game, the prices of the reps would reach some higher production costs which would reflect on the end price for the consumers.
LOL, na. Lots of shiny things are 3D scanned mate. As Muriamas says it's used a lot in the vintage car game, I've had very shiny parts scanned and reproduced.
You can use it for whatever you want, only your imagination is the limit. Keep in mind that these piece of equipment are really expensive and it's a big investment, maybe for that reasons replica watch factories don't use them.