ziprealty is really good about removing pendings from its list. Afterall, why have their agents waste their time over pendings. Yes there are some duplicate listings, I’ve seen Riverside being most problematic. SD and OC zip listings typically don’t see that.
I do agree that there are listings that DO NOT show up on ziprealty. maybe an “exclusive” listing by a REALTOR? but if your potential buyer is shopping on ziprealty, why would you want to keep your property away from being viewed?