Wired has a good article outlining findings related to real estate agents and their behaviours when selling a house. Holding out for an extra few percentage points when selling is not really worth the effort and so is not often done. The study this article is discussing compared ad wording and selling prices for homes sold by real estate agents versus ad wording and selling prices for homes sold by and owned by the agents. When selling their own homes bide their time and hold out for more money. Also, wording used in ads is telling. Less concrete words (e.g. well maintained, cozy) are hints to other agents to bid low and more concrete words (oak flooring) are hints to bid high. The name of the game is to move product at the most efficient combination of time on market and price for the agent.
One conclusion of the article is that knowing what's going on in terms of motivation, tactics, and language can put the person selling a home more in the driver's seat.