Flat Fee MLS Listings and Signage Explained
There are several reasons why you cannot put one of those familar red and white For Sale By Owner signs on your home if you are listed on the MLS. To put things in perspective lets break down what MLS isn't. MLS is not a platform for sellers to market their properties, it's a marketplace for real estate professionals. With this being said, once a seller contracts a local real estate agency to list their home on MLS, the home is not categorized as a For Sale By Owner (FSBO) listing.
The rules and regulations set forth by MLS usually  state the following with regards to For Sale signs. Only the “For Sale” signs of the Listing Broker may be placed on a Listed Property.
This statement is purposely vague and written to encompass the big picture.
If a seller contracts a broker to do a flat fee MLS listing prospective buyers will find the property while searching online. If the MLS listing piques the interest of the prospective buyer, there's a good chance the buyer will drive-by the property to check it out. If the prospective buyer sees a FSBO sign, they will most likely be confused because they most likely discovered the listing via an MLS partnership site or real estate agency online. Not only do these FSBO signs cause confusion for prospective buyers, but they also cause confusion for agents representing buyers. This is due to the fact that their is virtually no visual difference between a flat fee listing and a full service listing. Nowadays flat fee listings state the words: "MLS Entry Only" on the listing, but most agents don't know what MLS Entry Only menas. Much like prospective buyers, agents often pull up for the showing in confusion when they see that infamous red and white FSBO sign.
Over the years MLS and agents did everything they could to maintain control over listings. They have losened up control, but MLS is within their right to do everything to ensure MLS does not become a FSBO site. There are two things MLS will continue to do to protect their platforms. The will prohibit the use of FSBO signs and the ability to display seller contact information to the public.
 Usually - each MLS' has its own rules and regulations. I have looked through several and they all state the same thing in different ways.