Sure, it could be great to have clear precision about resource. To be logical, resources are used to be played like that :
A resource card is a type or card (like you have Character, support, event, story, conspiracy cards, all your card are potential resource card). You attach a card from your hand as a resource (p.8), it cannot be used for anything else. This card is considered to be a resource (point 10, p.5).
A Resource must be in an out of play state (Imagine you have a unique card in resource, you will never play another copy of this unique card, if resource was "in play" and keep its title, see rule of unique p.6 or imagine Sledge dogs placed in resource that gives bonus to your dog in play !).
Faq (Working effect) : Cards in play do not interact with cards that are out of play unless they specifically refer to an out of play state they will interact with.
So you can have cards that interact with resources if it is writing on the card (Servant says you to sacrifice a resource, Torch a joint destroys a non agency one, Twilight gate search a character...). It means also a resource card keep its faction value (the rule of the resource match or the example of torch a joint) and its original type (twilight gate, you must choose a character, not another type of card).
Woot! That's exactly what I was looking for, Dadajef. Specifically the Twilight Gate text.
Even if resources were blank save for their resource icon (and therefore considered in play), Servant from Out of Time and Torch the Joint could still technically function. Torch the Joint could easily be targeting resource icons as opposed to faction affiliations, as faction symbols and resource icons are identical and share implied affiliation. Servant from Out of Time requires no specific card text and could easily be targeting a blank resource. At no point have I theorized that resources "in play" retain anything other than their resource icon. To assume otherwise would invite swirling madness.
Twilight Gate is a different animal as it requires one to target a "non-Ancient One character attached as a resource," meaning resources, at the very least, retain their card type text. This alone is proof enough that resources do not and cannot exist "in play", that domains and their attached resources are almost certainly "out of play" zones. I realize this leads to additional questions (see another of jhaelen's threads), like, do we still control resources even though they are out of play? If not, how do we pay for Servant from Out of Time by sacrificing a resource we do not technically control (page 14, core rules, "A player can only sacrifice cards that he controls ...")? 50cc's of Golden Rule! STAT!
I also have to assume that KallistiBRC is correct in that cards cannot be exhausted in an out of play zone. That only makes sense. Exhausted, readied, insane; they're all game states that apply to cards in play. You can't exhaust a card in your deck, for instance. Also, Dadajef could easily be correct in that the Zoog resource icon on Burrow is a misprint. Either way, FFG needs to make something official.
So that's that! I have a card I can point to should this topic rear it's head in future. The magic bullet. Thanks to KallistiBRC, Dadajef and of course jhaelen for posing the question.
It does raise an interesting, somewhat related point (assuming I understand the mechanics): How can one target a "non-Ancient One character attached as a resource" if resources have no text box, and therefore no subtypes? If one wished to cripple Twilight Gate, a case could be made that only Zoog characters may be put into play. OR, more devious, one could say that Cthulhu (for example) attached as a resource no longer counts as an Ancient One. No text box, no subtype. Big Green back in action for a single phase, for a mere payment of 2? Honestly, the intention of the card is quite clear. Now I'm just being an ass for the sake of discussion ('cause yeah, this thread needs to be longer).