Point of introduction would prevent most problems. Lacing caches in Iraq with bad ordnance, should provide zero threat to Indian RPG users. I'm not talking about wholesaling the stuff. As for the chance that one of our guys would grab a bad round from the enemy and use it. I think the risk is already there, but more importantly that the benefit would far out way any possible flukes. Which ally of ours would have anything to fear from us lacing RPGs and ammo in Iraq with booby-trapped ordnance???? The friendly Iraqis shouldn't be using out of the same stockpiles, right? If you wanted to, you could put a non-obvious identifier on the stuff. Say one of those radio chip identifiers they're putting in CDs at WalMart. If one in every 50 RPGs that the terrorists had exploded when fired, it would cripple them. With a proper amount of publicity it could effectively deprive them of the use of the weapon.
Why bother to lace a enemy stockpile of RPG rockets when it is simpler to remove & destroy all the rockets in the ammo cache. Also unless you are planning to switch all the rockets in the ammo cache for your surprise packages you will in fact be leaving very real fully working AT ordnance lying around for the bad guys to use.