Do you think the GLXP will cause excessive advertising on the moon?
No, I don't. As mentioned in my previous answer, Google Lunar X PRIZE teams will almost certainly be reliant on private funding--which is to say venture capital, corporate sponsorships, and donations. Each of those revenue sources have a huge interest in making sure that the public is supportive of the winning missions, rather than turned off by them (donors because, well, they are the public; corporate sponsors because angering the public would defeat the purpose; and venture capitalists because they are in it for the post-prize profit, and post-prize profit won't be realized if everyone turns against the team).
I think the public outcry against gaudy advertising would be universal and fairly strong, so I'm very confident we won't see it. What we will see are the logos of the individuals, non-profits, and companies that made winning missions possible put onto the winning robots themselves, which strikes me as an appropriate recognition of the contributions of those people and entities. But it will be at a pretty small scale and, by my definition at least, well shy of "excessive".