Where do you draw the line on sharing with competitors?

Social marking has taken the world by storm and many of us want to  ride that wave of success found by being seen by thousands of people on social networking sites. Many people set up FAN pages hoping to grab some customers, and they post their offerings on a regular basis. They may join some groups and have some contests, but when it comes to sharing w/the competitor the network can get sticky.  For there are no norms set or rules set for what is proper etiquette.
Wikipedia - Etiquette

8x10 watercolor work in progress

I am a pet portrait artist, and this is a very popular art form that appeals to a broad audience.
Yet, in a weak economy the number of collectors or clients may be difficult to find. So, what does that artist do? Should they join other pet portrait groups - and possible have the client have the opportunity to compare? What about the FAN page, should they allow other artists to post their "Link"? Many people struggle with where they should sit on the fence, or if  they should hide behind the fence - hoping that their pet portraits are the only ones that shine on the FAN page so that  they can maintain client base.

I don't have a fence - I run free in the fields of artistic expression. No, I don't spam other pet portrait pages, but I welcome them to my page.  I have several of my FB buddies listed as a favorite on my  their comments - links and photos to my page and often times help them build their client base from my  hard work in establishing over 5,000 fans.

You may ask, why the hell would I allow other people - who offer pet portraits in the same medium on my page? Am I crazy!! - No, I'm not crazy. I feel that this is social networking at its best. Sharing links - profiles, and art together in the Facebook world brings good Karma.  I am not afraid that I will lose a customer because my friend paints great memorial rocks, or fantastic pencil art - or pop art. For all of our art is different, and we all should be seen so the client can get the very best option for his or her personal needs. I can't provide every option, though I do try, with my arsenal of pens, pencils, paints and products. The reality is I can't be the "ONE" for everyone - and if  I can allow my client the liberty to see what my friends offer, I am respected and offering good customer service.  I have no fear, for if they choose my friend over me, it is because they liked what my friend had to offer over mine. Art is in the  eye of the beholder. My husband doesn't like many of my portraits, but that doesn't make them not wonderful to my clients. They are a fan because I offer something they want at a price they think is of good value for the service rendered. Art collectors don't purchase on price - they purchase from who they know and trust. My clients know me, and I know them, so if they need a product I don't offer, I  might have a friend who does. Social networking to me is just that - social. If I only wanted to sell art, I would not be on facebook. For me it is about learning, sharing, and caring about all of the people you allow into your little virtual world.