- Learning as much as possible about a particular industry or vendor.
(Aviation, Airlines)
- Spending an inordinate amount of time communicating with other such persons on a bulletin board dedicated to that topic.
(Flyertalk, A.net)
- Being extrememly picky about the service provided by the vendor.
(Nope, I won't take them for the 31" pitch, gimme the 32")
- Engaging in endless speculation as possible upcoming changes and the reasons for recent changes.
(Is Emirates adding Vienna???) huh? huh?
- Knowing more about the vendor than many of its employees.
(A lot of people here can boast that, maybe not me)
- Having their friends and co-workers think ill of them for having such a strange hobby.
(possibly.)