[gav]

It really depends on the market. I've found that brand terms can convert really well if you can drive them to a targeted microsite or similar segmented area. Usually it means that the customer is far down the purchase funnel, a search for "washing machine" may be just research, "whirlpool washing machine" can mean the brand part of the decision is already made ("whirlpool duet" is even better).

[rfergie]

When I say "brand terms" I mean queries for the site's own brand. For example "washing machines on ebay". I've never seen these keywords not convert well; the question is how many of these people would convert anyway even without the advert.

[wildwood]

That's why it's so important to track the natural search traffic you're getting by search query, and line it up against the paid search traffic.

If you have strong natural search traffic on the term, then you should be able to scale back your bid on that paid search term without much risk.