There is one thing about touch spells that seems off when it comes to no visual effects - the lack of an AoO.
Unless you have improved unarmed strike, when you try to touch someone you will suffer an AoO. For some reason, when you cast a touch spell you are considered "armed" and don't suffer an AoO. Why the heck does your opponent treat your touch differently if there's not some sign that your touch is now deadlier than a normal touch?
Anyway, I think by the rules there isn't a glow, but that part has always bothered me.
Edit: As for the part where you cast a spell then go see the king and touch him, the spell is lost if you touch anything or cast another spell. Depending on the circumstances it could be quite hard to avoid touching something and discharging the spell. Certainly, if the character had to walk down a street, deal with the palace personnel, and be introduced to the court I can conceive of many cases of someone touching his hand (if only be accident) and discharging the spell. Certainly if the spellcaster holds his hand in such a way to avoid touching anything, that might look odd enough to warrant suspicion.
IceBear