It is amazing what information is available online now for a bit of internet sleuthing.
There is a quite new, large house 2 doors away from me that is built on a decent sized geological fault. As it is right on a rocky coastline the fault is clearly visible at low tide, both on the ground and on satellite imagery. When it was built they thought they had it easy as it was straight onto bedrock, unfortunately the piling in fault rock had to go far deeper than they expected to hit solid material. It nearly bankrupted the person building it and when it was complete they sold it immediately. No way in the world I would have bought that site (I do have geological training though).
Also, one of the 1st places I look is the SEPA flood map. Ruled out quite a few plots immediately using that.
One recent one I looked at looked pretty good on face value, nice aspect, passable size. I couldn’t really work out why it had been available for so long. It was only on streetview that the overhead powerlines directly over where you would want to build became apparent.