Alex Butin from freecause was on my Ethics panel (substitute for Paul Nichols) I'll paraphrase his response til the video comes out ... but I'm pretty sure he said it's up to the merchant to decide what's ethical. There is a good blurb of the session at http://blog.affiliatesummit.com/2009/01/16/affiliate-summit-west-2009-session-recap-ethical-issues-in-affiliate-marketing/

As for moving forward on the issue, although I stopped begging people to act I've had meetings with onecause, freecause, Linkshare as well as a call with Google Affiliate Network. Multiple calls with council and have been preparing a detailed report of actual events of overwriting but mostly the other more damaging events and actions. This is NOW much, much, much bigger than a Walmart link being overwritten durring black Friday and covering it up - it's about the long term viability of the channel and the life or death of a network or two who crossed many lines and broke way too many rules (yes real rules not just the ethical ones we all see).