Thankfully Casascius is that guy. I have seen a half dozen threads like this and they all ended up being typos. It is pretty easy to do since the writing is very small. A good magnifying glass helps. It would be nice if clients and websites stated "this is an invalid private key" as opposed to incorrectly stating the "balance/value is zero". There is a reason for the SHA256 check (ignored by AFAIK every website and client).
bitaddress.org does check.