Each to his own of course - although when I come to sell, I hope I get one of the "no sea trial guys"

I guess that there are a number of things that you'd check or recheck under actual sea trial conditions :
Engine performance under load, when heeled, when properly warm. Restart. Charging. Cooling.
Gear box ditto.
Standing rigging, running rigging, sail hoisting, condition, furlers etc. Rudder. Propwalk
Water leaks appearing.
Odd sailing/ motoring tendencies for example significantly better performance on one tack.
Unexpected clanks and rattles.
Instruments. Radar. AIS
Now I know you can do some of this on the hard or alongside, but even then only by actually sailing will you find intermittent or load related faults. Even on our trial the alternator revealed its intermittent charging and a sheave blew under load. Not at all major but only spotted at sea. I sailed on one boat where the owner had drilled an extra drain hole for the anchor locker - only noticeable on starboard tack, but then REALLY obvious!
I suppose my view is why not have a sea trial?
Cheers
Bristle