I couldn't believe I was actually contacted by a company since im a really small business without a lot of customers about using their trademark. I was forced to take down my picture of a cake that wasn't sold but was still on my business page. Has anyone else ever been contacted before by a company ?

i had the same experience on etsy. i had angry birds cupcake toppers listed and they asked me to take it down due to copyright infringement. i guess we can't do anything about it as those as copyrighted. 

Yes, you need to be careful.  There are a lot of lawyers out there, and I also think the etsy admins keep tabs on this stuff too.

On the rare occasion I make a character cake, I never put it on my facebook page.  I also discourage people from ordering them.

AIf you described the cake with the name of the trademark, it is trivial to find the cake with a Google image search and track it down to your page. You may want to take this opportunity to remove any other pictures of cakes made with copyrighted characters (Disney, Mario, Star Wars, etc.).

To protect against this, you need to obtain written permission from the owner of the trademark or copyrighted element before you copy it.