This question helps to find what we like in watches and can even help us choosing the right one (we see from time to time people getting rid of a watch a few weeks/months after buying it).
Well, first, I take a very long time studying, trying the watches I like. After several months, I know perfectly what are its pros and cons and... if I still want it.
So, to answer your question, how do I finally come to that point when I would be eager to "have that watch".
The watch in itself is important but I think we can't underestimate the impact of marketting, the history of the brand and all that "spiritual stuff" that flies around it.
If I was to sum-up, I would say:
- The Beauty of the design: case+dial layout+bezel, the colors, the material... all these must appeal to me and this is very subjective. A watch about which I don't like the look, and it stops here.
- The Beauty of the movement (finishing)
- The movement technic, especially when it is different and brings something else (in material or engineering)
- The spirit of the brand, especially when it's an Independant.
- The discussions between owners or reviewers are something I like to hear.
I think these are the main criteria for me, even if nearly all the possible reasons you mentionned come into play (with a different weight).
Too much ambassadors, too much saying "we have a 100 history" when the brand has just been reborn, too much bling bling and superficial communication, a horrible salesperson... are things that can prevent me from buying a watch and break the enthusiasm.
Cheers, Mark