In newer areas, well-platted subdivisions and for properties that have changed hands recently, a real estate agent can usually safely assume that documents supplied by the seller will validate the merchantability of the property. That's not always the case in rural areas or for properties that have been in current ownership for many years.
A very important part of the listing agent's job is to assist their seller client in gathering the information necessary to accurately present their property for sale. This could include deeds, restrictions, surveys, access documents, litigation records,etc. With properties that have been in a family for generations, it's very possible that there has never been title insurance purchased. There may even have been no abstract of title prepared. It's imperative that the seller, and a title company if possible, gather all pertinent documents and that they be examined to verify that title insurance can be purchased and that there is legal access to the property.
Access and code problems can also be present when larger parcels are subdivided for sale. Has the seller met the local ordinances for legal subdivision of the property? Is there insurable access, such as a road easement to access the new parcel. As the seller's representative, don't rely on the buyer's agent to require documentation of a recorded access easement across the other parcel after the division of the two properties. If the seller doesn't get this resolved and the buyer's agent doesn't catch it, you could have litigation down the road from future owners who run into disputes over access.
An actual situation makes a great example:
A seller has owned three contiguous parcels for over ten years, one with a home on it. They want to sell all the property and believe that it would be easier to sell as one residential parcel and two adjacent land parcels. One 30 acre piece catches the interest of a buyer. We're working with a listing that's nine months old here. The buyer's representative is concerned that two parcels of private property, as well as a piece of U.S. Forest Service land are crossed to access this parcel. When the listing broker is told that an offer will only be made if there is some idea of the insurability of access, the seller starts working on it then. It is determined that one of the two private owners does not want to grant an easement. In this state, prescriptive easement action can take years to secure. The distance across the middle parcel makes a new roadway on the owner's properties too expensive. The buyer goes away and the seller is now trying to figure out what to do.
This example is a hard one, as there are four parties that are damaged in some way. The seller has no sale, the buyer can't buy the property they want, the buyer's agent gets no commission and the listing agent has marketed a property for nine months that wasn't viable for sale. We shouldn't cry for the listing broker too much, as they could have avoided the situation entirely by doing their due diligence on the property's documents at the time of listing.