Quadrille - 8:16 am on Dec 28, 2008 (gmt 0)

It all depends on your POV.

If my product/service is interchangeable with "trademarked keyword" then I don't see an ethics issue.

Site A contains the "trademarked keyword"; site B does not. The searcher searches for "trademarked keyword", and is given Site B in preference to site A.

That may not be an ethical issue for you, but it may be for the searcher, and it certainly is for Google.

On a more practical point, unless site A has no SEO clue, there is no 'ethical' way that site B can conceivably come out on top in the serps.

What you do is, of course, up to you - but be under no illusions that this is a matter of

1. Depriving site A of a visitor
2. Diverting the visitor from an expressed choice of site
3. Distorting the serps, potentially damaging users' faith in the SE.

Whether these points are important is a matter of personal choice ;)