What's wrong with Jamba Juice's Get Your War On plagiarism

Below, Xeni posts about Jamba Juice's outrageous plagiarism of David
Rees's brilliant Get Your War On webcomic. Like many of Rees's fans, I'm
also pissed off by this, but not because of "theft" or "infringement"
-- as Rees himself points out, he uses a bunch of public domain clipart
to make his work; if the roles were reversed (funny webguy uses the same
public domain art as big company to do something that subverts the
original), we'd all be crying fair use, and rightly so.

No, what pisses me off about this is that it's plagiarism. The
unsigned Jamba Juice ads look like they're Rees's work. Even a
sophisticated person who's familiar with both Rees and Jamba might
mistake one for the other.

This may or may not be illegal -- you could argue that Rees has a
common-law trademark claim against Jamba -- but it is certainly
unethical. It's sleazy. It fools the public into thinking that Jamba
Juice has an endorsement that it just doesn't have.

It's easy to get caught up in property talk here and declare that Rees
owns clip art, or clip art with funny speech bubbles, or what-have-you,
but Rees isn't doing that and we shouldn't either. We don't need to
invent exotic new copyright laws that confer ownership over clipart to
condemn Jamba Juice: we can make recourse to the tried-and-true
principle of not tricking people into buying your products and not
plagiarizing other people.

Jamba Juice accused of stealing "Get Your War On" artist's work; GYWO calls for boycott