Gavin Andresen - 2012-03-23 13:30:45

@s{quotedtext} @s{quotedtext}
That statement is incorrect.

There are two ways you might waste time hashing:
1) Put a bad BIP16 transaction in your block
2) Building on top of a bad block produced by somebody else

So even if you don't include anybody else's transactions in your blocks you will still almost certainly waste some time hashing by building on top of invalid blocks produced and announced by some other lazy miner running an old version of bitcoind.