For a plot of land, I would go out there as often as possible. Of course, you ask the real estate agent if you can take another look. But since he already thinks he has the buyer on the hook, he will say yes.
For us, some characteristics came up through conversations with the neighbors about a plot of land that the agent had forgotten to mention:
The plot (at the head of a nice little dead-end street with fairly new buildings) was not connected to the street. The frugal owner had refused this and had planned a connection to a building located quite far back on his property. Result: long utility lines, a private road at the back, and no parking allowed in the front.
There were wild plants there that need a lot of water. All the old buildings in the area had their own wells in the basement; the new buildings had either waterproof basins or wet feet.
A mixed-use area was immediately adjacent. In the neighboring old building, an enthusiastic person bred pigeons, many pigeons. Practically uncontrollable.
Another neighbor occasionally sprayed marking paint on the plot for sale, indicating where one was not allowed to build despite the building envelope so that he could easily turn around with his almighty SUV. I once stood on the plot while he was maneuvering there, and he pressured me with his vehicle.
All of this only came out bit by bit. The last restriction was revealed to us two days before the notary appointment. We actually only found out because we talked to the people more than once and they took us seriously.