Okay, despite my earlier fail, some of the previous questions still apply. Even if no one is there/can see Recluse, there is still a lot of technology lying around there. There's the medical facilities and an entire wing devoted to extradimensional experiments within his headquarters on just the ground floor. The medical devices work off of stolen alien technology, which can scan and diagnose a person in seconds, even if they can't cure them. Would that show anything? There are also sensors that could be accessed in the lab areas that NPC chatter has mentioned at times, and some NPCs seem to be holding, that seem generally available around there.

In short, if Recluse used either an advanced, alien medical diagnostic tool or a scanner specifically designed to detect extradimensional anomalies, would anything out of the ordinary come up? This sort of question might also carry over to people like Star Trek cast, what with their magic boxes that go 'ping' and tell them everything.