user323: I'm currently doing some double-spend testing, and it appears that the standard client prefers broadcasting transactions that credit its wallet. That is to say, a client that receives such a transaction broadcasts it more, than it would broadcast other transactions in hopes of getting it into a block sooner. Is this truly the case, or are my observations incorrect?

user1725: According to the Satoshi client transaction exchange behavior, this does not seem to be the case. However, that page isn't written well.  Looking at the actual source code, I cannot see any special behavior for transactions to an address in your wallet, but I do see special behavior for transactions from such an address.
Thus, I do not think the behavior you observed is actually valid, and is more likely a pattern you noticed because human beings are too good at noticing patterns for our own good.

323: <p>I'm currently doing some double-spend testing, and it appears that the standard client prefers broadcasting transactions that credit its wallet. That is to say, a client that receives such a transaction broadcasts it more, than it would broadcast other transactions in hopes of getting it into a block sooner. Is this truly the case, or are my observations incorrect?</p>
 1725: <p>According to the <a href="https://en.bitcoin.it/wiki/Satoshi_Client_Transaction_Exchange" rel="nofollow" title="Relevant wiki page">Satoshi client transaction exchange behavior</a>, this does not seem to be the case. However, that page isn't written well.  Looking at the <a href="https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp" rel="nofollow" title="main.cpp file, which contains the relevant functions">actual source code</a>, I cannot see any special behavior for transactions to an address in your wallet, but I do see special behavior for transactions from such an address.</p>

<p>Thus, I do not think the behavior you observed is actually valid, and is more likely a pattern you noticed because human beings are too good at noticing patterns for our own good.</p>
