Maybe even block your driveway with orange cones... buyer's agents showing the house may otherwise pull into your driveway, implying to a reasonable client that access to that driveway comes with the home - this sort of "implication" to a "reasonable person" is where otherwise reasonable people can get into disagreements! 

I know some of the smell could also be in the carpet and pad (which is being REPLACED), so should the concrete subfloor under the pad also get coated in the same odor-blocking primer?

I'd be happy to look into this for you and get you a concrete answer on how these properties came to get this sign and how (if it is possible) to get rid of it, but I would need to be compensated for my time. 

what block, interested, dm me?

On a slab foundation the soil should be 4-6 inches below the top of the concrete but if it is not, and the soil gets saturated one of two things (or both) happen.

East Bay AreaI have a 2' x 2' concrete that had sunken down one inch.

You need concrete info from locals.

Apparently many real estate firms block flat fee listings from feeding to their customer’s automatic search results.

I never want to really make someone mad and have concrete poured down the drain. 

@Patrick Philip Well, the other three being in a historic district does make a difference...the People who like historic district properties generally pay more than for a comparable house not in a historic district, and historic property renovations generally cost more due the restrictions.This is a case where 1/2 mile away are Not comps...many times just a block or two across a major road/subdivision boundary are not comparable.Also, the more sf you have in comparison to comps, the lower the $/sf value you have.....a 1900sf 3/2 in the same neighborhood won’t have the same $/sf. as a 1500 sf 3/2.