Do you Like the Fan pages of your competitors?

Many of us have received requests to "Like" a fan page of another Real Estate Agent or Real Estate Company. 

At one point or another, you have probably Liked the Fan Page of another agent working in the same city or area as you do, is it a good idea though?  Unless you hide your Likes from your Facebook Profile Page, your friends (which may include past clients) will see that you have endorsed one (or more) of your competitors.  Even if you do hide your Likes, one of your friends may happen to visit your competitor's Fan Page; Facebook will show your friend other people who Like the agent's page and they may see you are one of the agent's Fans.

If you choose to ignore agents' requests to Like their fan pages, will they be offended?  Should agents even send Like requests to fellow agents?  Would it not make more sense to have Likes from people other than (primarily) real estate agents? 

What is the proper etiquette when dealing with this aspect of social media?  How many Fan pages of competitors have you Liked since joining Facebook?