LegateFasendil
Imperial Legate
I'm not even sure why we're debating this, it is well established that information extracted through physical pain is unreliable. Hence why other methods are used in conjunction with pain.
The desire of love was merely one example, and as it states it isn't for extracting information. You can't break someone's faith through beating them, you can't make them betray their God and other followers by force.
If Talos worshipers can give up their God and other fellow worshipers through pain, then Talos is screwed.
"My oath to Stendarr is stronger than any suffering you can inflict on me." - Adalvald
Stendarr's followers aren't so easy.
I think it is very much reliable considering the fact that an overwhelming amount of people simply do not like being in such physical pain. It is simply the negative side effect for being a mortal, and therefor it's so easy to exploit to get information out of people. Like I said before the Thalmor are finding new methods to use to against the Nord's of Skyrim. Forcing their Nordic prisoners to confess by revealing them secret locations to their Talos worship shrines takes extreme measurements.
Adalvald is all words and no action. He was given a quick death, and didn't even the time to react from the pain. I don't think his oath to Stenndarr would mean much once his pain receptions started taking an effect... once he actually started feeling pain from being tortured by his vampire capture.
Pain is effective however pain is temporary. A strong enough mind can literally ignore pain, not just block it but not even allow it to register, like those Special Forces people. Pain is not the only tool for breaking one's spirit, however for the simpletons, pain is really all it takes. And there are different forms of pain too.
There are however, always exceptions.