I have actually asked sandicor (who oversees rules regarding San Diego Realtor advertising) regarding this sort of ad.
Per them, until a sale is final and closed (ie: the title has shifted to the new owner) agents can advertise it. The DRE is, in my experience, less restrictive than NAR, CAR, SDAR, or Sandicor.

Complaining to DRE is unlikely to have an effect.
Advertising a place that has not yet sold is not illegal, (professionally) unethical, or false advertising.

That being said, I agree with you. It seems really cheesy to be throwing out ads for a place that has a deposit on it already. You might have some luck in approaching the senior broker or office manager of the team or agent in question. That is what I would do.