But you do lose XP if the spell is not on the list, no matter what. Maybe I'm just not getting what you are trying to say. Try wording it in a completely different manner.
Why would you research what spells you can affect with Permanency? The way I see it, you only lose XP when Permanency works (i.e. makes the spell permanent). Now, when you use the trial and error method (you cast Permanency on a spell of which you do not know whether or not it can be made permanent, because you haven't researched it), you don't lose XP when Permanency fails, and you do when Permanency works. This way you save yourself time and money.
Example:
When the PHB was released, the Blindsight spell (MoF) didn't excist yet. You want to make this really useful spell permanent, using Permanency. You don't have the money to do extensive research, but you decide to try it anyway.
First, you cast Blindsight. The next round, you cast Permanency. Now there are a couple of things that can happen (personally, I would choose one of the first two):
1) You feel nothing (you don't lose XP). Permanency didn't work. This is either because you level is too low or because Blindsight can not be made permanent.
2) You feel weakened (you lose XP). Permanency did work.
3) Something else.