The Lazy One never "perceived the casting, the spell's effect or both", so no, you can't determine "every spell on the target" just by looking.
Plus, Trance of Order only allows you to treat results of 9 or less as 10. WIth 10 INT, that's +0, so Trance of Order doesn't help you, turning results of 0-9 into 10, because that's a 10 and the DC to identify a spell you witness is 15+spell level. That's a range of DCs is 15-24, so changing a 4 into a 10 results in the same failure. Are you saying that the Lazy One's strategy is to never ever dispel when he doesn't detect a spell, which means he never dispels Contingencies, for exemple? (DC 21, that's impossible to understand for him even if was witnessing the spell being cast). That's totally contrary to what you said upthread about his strategy, insisting on his ability to cast dispel subtly... while he very rarely dispels and only on target who cast low-level spells.
Yes, that's the way the OP has to introduce strange readings of the rules. I think the "Calvinball" reference earlier was a very good approximation of what must be happening at his table.