This article talks about homeowner’s right to a for sale sign, even if their association does not allow it. http://query.nytimes.com/gst/fullpage.html?res=9A05E3D91F3BF934A25752C1A960958260
Personally, I am the type of person who would fight the fight, and I suggest you keep this article if you live in an association. Some things are worth fighting for, and a for sale sign is paramount to a successful sale. I have been told by many homeowners that their association is no longer doing battle over this issue for fear of a lawsuit.
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