Over 4700 active listings (55%) in the Bay Area have been on the market for over 60 days; over 3100 (36%) have been on the market over 90 days (since before the autumn selling season began). The only thing wrong with most of these is that they were overpriced to begin with, and have now been left behind by buyers, stigmatized because they didn't sell. Most of these sellers and listing agents are still eager - or even desperate - to sell these listings: Leverage the situation, earn your commission, and make your buyers happy and grateful.
December is the greatest opportunity of the year for buyers to aggressively negotiate really good deals. For every buyer not in contract, conduct an entirely new search, focusing especially on listings with longer DOM. If listings are attractive to your buyers, make offers at whatever price they'd be very happy with. Don't worry about offending sellers with offers that are "too low," don't bother asking listing agents what their sellers will or will not consider.
Don't overthink it: Throw in aggressive, even very aggressive offers, and see what sticks. It will likely result in additional deals - I've heard this from many surprised and happy agents in the past.
I took a quick glance at Sacramento listing stats, and the percentages are very similar. I suspect they're similar almost everywhere in the country.
Below is an outline of Basic Principles of Negotiation, as well as ways and scripts of getting Price Reductions on unsold listings.
Asking for the Price Reduction Basic Principles of Negotiation