I believe many sellers already know the answer to the question and may only be asking their real estate agent's opinion to confirm their belief.
Compared to other home improvements, painting is a cheap "nice touch" so why not?
Additionally, while preparing a home for the new paint sellers can deal with another issue which I call "showing your everything" Removing excess pictures and other personal items from the walls and displays will allow prospective buyers to focus on a home's characteristics.
In any market the tiniest advantage is still an advantage.
Fresh paint will always give a house a fresher and newer look. If a home is vacant the walls (and floors) are going to get a lot closer scrutiny.
A poorly prepared property will not bring a buyer as quickly and as much money as a well prepared, well staged, clean, competitively priced property. I would even go another step and recommend a pre-listing inspection be conducted to assist in your preparation.
Considering selling your Viera, Suntree or Rockledge, Florida home? Call me at 321-693-3850 for a free market analysis.