
(Have an underwhelming feeling this has already been thought of, but here goes).
The premise is, following an incident with an escaped entity/object, the Foundation became aware of a perfectly ordinary human being, a former bank manager, Mr James Smith (whom we shall refer to as SCP-3566 from now on). SCP-3566 exhibits the involuntary ability to cancel out or neutralize any anomalous object and its properties within its direct vicinity, or line of sight. Nothing appears out of the ordinary to 3566.
To demonstrate:-
A test with SCP-682, would briefly have the alarmed monster cry out in pain and convulsions as it transforms into an ordinary, if somewhat enlarged for its species, Komodo dragon. 682 in fury tries to attack and maul SCP-3566, forcing the latter to vacate the premises. 682 returns to its regular abnormal-self clawing at the door. 3566 returns with armed guards who this time successfully terminate 682, which is confirmed dead. 3566 comments to kill such a creature with assault rifles was unnecessary and cruel. However, as soon as 3566 leaves again, 682 transforms back and resurrects itself, hurling all manner of verbal abuse and profanity at the door.
Despite this, SCP-3566 is still but a mortal, and can die from SCPs, but their enigmatic (sometimes inexplicable) characteristics, are effectively negated for so long as he is accompanying them. For this reason, 3566 is deemed very useful in the moving and relocating of the more dangerous entities.
This has its downsides, the more beneficial objects such as SCP-500 for example, will have no more effect upon injuries than a placebo, or impact upon a contracted disease than a Paracetamol.
The positives: It would be amusing for 3566 to consider the Foundation an enormous waste of taxpayer's money since he never sees anything worthy of containing away from the public, not to mention, the article could get quite a lot of interesting cross-article tests, from 3566's perspective.
The negatives: That's a lot of work, and I'm lazy. :)