I suggest an upfront talk with your realtor, ideally would have already been done. Our realtor (who we have a long relationship with) has been willing to help us with FSBOs, and also has a paperwork only fee structure. If your realtor has spent time on your behalf be considerate even if it doesn't result in the sale.

A Google search has several articles about your question. I'm not a realtor, but I live in a lakefront community with many part-timers from the big city. According to the Google articles, many realtors will let you add people to an exclusion list because those potential buyers generally do not pan out. YMMV.

Did you give the 4 potential buyers a price? That can make a difference in how interested they are. Sometimes it just takes people time mentally to get it together to buy something big like a house--especially, if your home is older and might need work. Make sure that you give them a price and tell them that you already have several interested (don't say who) and that you will be putting it up on the market ASAP. I would think that would light a fire in those that are really interested. Some people are just nosey or are looking for a bargain. They are not going to get a bargain in a seller's market.