I do not believe in conspiracy theories in the electronic stock market. Only people's incorrect understanding of the trading systems they are using. If you have an example we (this forum) can try to explain it.
I think Don is mixing up ARCA (which should show up as PSE or PCX for lited stocks on any up to date system) and Nasdaq Intermarket and its CAES execution system (usually displays as NASD or THRD; Instinet used to quote via that same identifier in certain stocks). As of next week CAES should be history, though, as it is being replaced by Supermontage. And that should also be the end of any moral hazard on the part of Nasdaq MMs in listed trading.