Somebody asking "is my ESN is clean" doesn't sound right...
It's like somebody asking "is my car's VIN clean". The only reason you should even be asking is if it's NOT YOUR CAR.
About the only ways an ESN gets blacklisted is if the phone is reported Lost/stolen, the account goes into delinquency, or there is an insurance claim made on it.
In ANY of those cases ownership of the phone reverts to VZW or the insurer (ok, minor exception if the phone is lost and then recovered by the owner, without filing an insurance claim. But then they should be able to just get verizon to unblacklist the phone). So if the ESN is bad, the phone is in all likelihood STOLEN.
If it's in an original box, it should have the MEID on the box (I'm guessing even if it doesn't have the factory box, if it's from assurion it will have it on the box)
(ok, I'll admit I'm might just be grumpy from doing Partial Differential EQNs for the past hour and a half. The OP might just be unnecessarily thorough with this.)